mm 




COPYRIGHT DEPOSIT. 



BALDWIN ON HEATING; 



OR, 



STEAM HEATING FOR BUILDINGS 
BEVISED. 

BEING A 

DESCRIPTION OF STEAM HEATING APPARATUS FOR WARMING AND 

VENTILATING LARGE BUILDINGS AND PRIVATE HOUSES, WITH 

REMARKS ON STEAM, WATER, AND AIR, IN THEIR 

RELATION TO HEATING; TO WHICH ARE ADDED 

USEFUL MISCELLANEOUS TABLES. 



WILLIAM J. BALDWIN, M. Am. Soc. 0. E., 

Member American Society of Mechanical Engineers. 



SW^itJ maiifi Kllustrations. 



SIXTEENTH EDITION, REVISED AND ENLARGED. 
FIKST THOUSAND. 



NEW YORK: 

JOHN WILEY & SONS. 

London; CHAPMAN & HALL, Limited. 

1908 



i\Ar?j\i 



[uBRARYof OONGRESS 
TwoCooles rteceivbd 

JUN 1 1908 

'aowri«ru tntrir 



Copyright, 1881, 1897, 1908, 

BY 

WILLIAM J BALDWIK. 









ROBERT DRUMMOND, ELECTftOTYPER AND PRINTER, NEW YOKE 



This Book is Respectfully Dedicated 

TO 

MB. and MRS. -WILLIAM DOUGLAS SLOANE, 

IN CONSIDERATION OF 

THE GREAT CHARITY THRIR BOUNTY HAS CREATED AND MAINTAINED 

IN THE 

SLOANE MATERNITY HOSPITAL, NEW YORK, 

AND 
THEIR CONCURRENT INTEREST IN THE SCIENCE OF 

WARMING AND VENTILATION. 



INTEODUCTION. 

It was within tlie twenty years previous to the writ- 
ing of the first edition of this book (1878) that the warm- 
ing of buildings with steam carried through pipes be- 
came anything like a science ; previously, it was a 
"chaotic mass of pipes, and principles," and even at 
the present time there is much blundering by persons 
who, being in some of Ihe other engineering branches, 
imagine any one may do steam heating without any 
special training. 

A low-pressure gravity apparatus is a healthful^ 
fairly economical, and pretty perfect heating appli- 
ance, and may be constructed to heat a single room, 
or the largest building, with a uniformity which can- 
not be attained by any other means, except, perhaps, 
hot water. 

By a gravity apparatus is meant, one without an out- 
let, whose circulation is perfect, wasting no water, and 
requiring no mechanical means to return the water to 
the boiler. It may with a hot water apparatus be 
likened to the circulation of the blood — the boiler 
being the heart; the steam-pipes^ the arteries ; and the 
return-pipes^ the veins ; thus carrying lieat and life 
into every part of a building. 

When reference is made to steam-pressure in this 
volume, it is understood to mean pressure above the 
atmosphere. Nearly all tables of reference on steam 
are given in absolute pressures — namely, pressures in- 
cluding the pressure of the atmosphere — which unap- 



iv mTBODUCTION. 

parent pressure has to be overcome before it is appre- 
ciable on a steam-gauge. As the steam-fitter has little, 
if anything, to do with pressures below atmosphere, 
the tables, etc., herein used will be modified, to com- 
mence at atmospheric pressure (14.7 pounds of the 
absolute scale), thus conveying comparison in the 
ordinary terms to which the steam -fitter is accustomed ; 
and preventing the necessity of a mental calculation^ 
which always involves fractions and enjoins a task 
which should not be thrown on a practical working, 
man or a beginner. Therefore, all pressures men- 
tioned will be apparent ^pressures — namely, pressures 
which would be indicated by a properly regulated steam- 
gauge. 

An endeavor will also be made to confine the work 
to facts as developed by practice, experience and ex- 
periment, refraining from comment and opinion except 
where the want of an explanation might lead to error 
or misunderstanding. 

The first part of the book will be devoted to the 
principles of heating apparatus, etc., and the latter 
part to the details and to an amplification of such 
parts as are likely to change. 



PREFACE TO THE SIXTEENTH EDITION. 

In 1879 the first edition of this work appeared. It 
could be called nothing more than a collection of 
suggestions or hints, as stated in the preface of the 
earlier editions. These earUer editions were the pub- 
lisher's editions, being reprintS; with sUght corrections, 
but without revision. So far as the work related to 
the principles of steam heating, where the water of 
condensation is returned by gravitation to the boiler, 
there could be little change in the book. To bring it 
down to modern practice in the use of steam by other 
methods, a general revision was necessary. Therefore 
the whole former book is superseded by one whose 
date and practice harmonize. I therefore endeavor to 
give some facts relating to the principles of modern 
steam fitting, which, since the writing of my first book, 
has risen to the dignity of a branch of engineering 
science that may be known as domestic engineering, 
and which includes substantially all that goes to make 
up the engineering plant of a modern city building, 
excepting the electric light and elevator systems, which 
do nut properly belong to the subject. 



vi PREFACE TO SIXTEENTH EDITION. 

The order of the old book has been maintained 
as much as possible, and the chapters retained are 
modified to conform with the present improvements in 
practice. The same, or nearly the same, title is used, 
and the book in its old form will be withdrawn from 
the market. 

The Author. 



CONTENTS. 



CHAPTER PAOB 

1. Gravity-circulating Apparatus 1 

II Radial ors and Heating Surfaces 27 

III Classes of Radiation 43 

IV. Healing Surfaces of Boilers. ;.... 56 

V. Boilers for House Heating 63 

VI Forms of Boilers Used in Heating 70 

VII. General Remarlis on Boiler Setting and Construction 99 
VIII. Proportions of the Heating Surfaces of Boilers to the 

Radiating Surfaces of Buildings 107 

IX. Grates and Chimneys 113 

X. Safety Valves 128 

XI. Draft Regulators 143 

XII. Automatic Water Feeders 148 

XIII. Air Valves on Radiators 154 

XIV. Steam Pipe— Size, Area, Expansion, etc 164 

XV- Size of Main Pipes for Low pressure Steam-heating 

Apparatus, and Why Such Sizes are Necessary. . . . 181 

XVI. Steam 192 

XVII. Heat of Steam 200 

XVIII. Air 206 

XIX. High-pressure Steam Used Expansively in Pipes for 

Power and Heating 218 

XX. Exhaust Steam and Its Value 233 

XXL Exhaust-steam Heating 241 

XXII. The Separation of Grease from Exhaust Steam 251 

XXIIL Boiling and Cooking by Steam, and Hints as to How 

the Apparatus should be Connected 260 

XXIV. Drying by Direct Steam. 277 

XXV. Drying by Air Currents 287 

vii 



Vlll 



CONTENTS. 



CHAPTER PAGE 

XXYL Steam Traps 292 

XXVII. Valves for Radiators. 305 

XXVIII. Remarks on Boiler Counections and Attachments 312 

XXIX. Data on Coudensalion in Radiators 318 

XXX. Pipe Covering — Wliat is Saved Thereby, and Other 

Data 339 

XXXI. Miscellaneous Notes 345 

XXXIL Fire from Steam Boilers 351 

XXXIII. Steamer-heating Data 357 

XXXIV. Miscellaneous Notes and Tables 375 

Index , 393 



CHAPTER I. 

GRAVITY CIRCULATING APPARATUS. 

What is knowu as a low pressure gravity cir. 
culatiug apparatus is one in wliicli the water of con- 
densation from radiators and pipes returns to the 
boilers of its own weight without the assistance of 
mechanical contrivances. It is the apparatus used in 
warming private residences and sometimes churches 
and schools, though many large churches and schools 
at the present day have electric lighting or fan engines 
and pumps, the exhaust steam from which is of so 
much value that the gravity apparatus will probably 
soon be ussd only in the warming of private resi- 
dences and detached buildings where steam for 
warming purposes alone is required. The term 
low-pressure is a very general one, and usuaUy 
it is accepted in the trade as meaning from atmo- 
spheric pressure to a pressure of about 10 pounds 
above it. An apparatus, however, that will work pro- 
perly and refcarn its water of condensation into a 
boiler at 10 pounds will work equally well at any 
higher pressure, and then it is simply called a gravity 
apparatus, and sometimes known as a high pressure 
gravity apparatus. 

There are four systems of low pressure steam piping 

in use. . i . • 

The first, and probably the best known, is what is 



STEAM HEATING FOR BUILDINGS. 




GRAVITY-CIRCULATING APPARATUS. 3 

to-day designated as the two-pipe system, in wliicb 
the main return riser is carried below the water line. 
An example of it is shown in Fig. 1. 

The second system employed is known as the sepa- 
rate return pipe system. It differs from the first in 
that the return pip© from every coil and radiator is 
carried below the water line of the boiler directly 
from the radiator before it joins and connects into the 
return pipe. It consists of the main horizontal dis- 
tributing pipes, distributing risers, and a main hori- 
zontal return pipe, corresponding to the main dis- 
tributing pipe, to which is connected the separate 
return risers from every coil or radiator ; the returns 
not, connecting with each other until they go below 
the water line of the boiler. (See example in Fig. 2.) 

The third system of gravity return consists of a 
main distributing pipe with distributing steam risers, 
including corresponding return mains, but no return 
water pipes from the radiators. The distributing 
riser carries the water of condensation back within 
itself to a relief pipe, carried below the water line, 
connecting with the main return pipe on the basement 
floor, which conveys the water into the return system, 
and thus to the boiler. This system is shown in Fig. 3. 

Fig. 4 shows a modification of this system, in 
which there may be said to be no return pipe. The 
steam pipe A starts from the boiler and runs all 
around the building of large diameter, gradually 
pitching downward to the point B, where it drops 
suddenly below the water line and enters the boiler at 
C. This steam loop of large diameter around the 
whole basement becomes substantially a part of the 
boiler. The rising lines D D start almost directly 
upwards from it, and the water of condensation falls 



STEAM HEATIXG FOR BUILDINGS. 



back within the same and goes on with the steam in 
the direction of the arrows to the point C^ where it 
enters the boiler. 

A connection of small diameter — about a, one-inch 
pipe— between the main steam-pipe A and the main 
return pipe B-C close to the boiler will be found to be 




Fig. 4. 

an advantage; as it causr^s a steadiness of the water both 
in the boiler and in the vertical return pipe B-C. A 
globe-valve may be placed in this pipe as "a choke" 
for adjustment. 

There is a still simpler form of gravity return, and 
usually applied only to a very small building, which 
is shown in Fig. 5. In this case the diameters of the 



GRAVITY-CIRCULATING APPARATUS. 5 

pipes in the basement are large and the horizontal 
distances short, and the steam pipe, when it leaves the 
head of the boiler, instead of dropping or pitching 
downward, runs upward at as steep an angle as pos- 
sible. In this apparatus all the water of condensation 
from the radiators has not only to fall back within 
the steam rising line, but has to find its way back 
through the nearly horizontal main steam pipe into 
the boiler. If the pipes are sufficiently large in diam- 
eter the water will gravitate to the boiler in opposition 
to the steam flowing the other way. 

System No. 1 can be run at cmy pressure, providing 
the pipes are sufficiently large in diameter and properly 
arranged ; and it is the system commonly used in 
large buildings, both in the case of gravity appa- 
ratus and where exhaust and waste steam at very 
low pressures is used. It is well to add here that any 
of the system of piping just shown, excepting that of 
Fig. 5, which is purely a small house heating appa- 
ratus, will work under exhaust steam pressures 
slightly above atmosphere if the diameters of the 
pipes used are sufficiently large and slight modifi- 
cations are made as mentioned elsewhere under ex- 
haust steam systems. System No. 2 is generally used 
in private houses, and in buildings where extremely 
low pressure is emploj^ed, and with any of the first 
three systems can be made perfectly noiseless, when 
done with care, and there is rarely any difficulty in 
expelling the air when radiators are used. 

For those not acquainted with the technical 
names of the different parts of a system, and to pre- 
vent misconception, the following explanation of terms 
is given. The same names always apply to the same 
part of the circulation, no matter what the system. 



6 



STEAM HEATING FOR BUILDINGS. 



The word circulation here means the whole distribu- 
tion of pipe in any one job or apparatus. 

The Main Steam or Uistrih ating Pipe. — The nearly 
horizontal live-steam main, generally near the cellar 
ceiling. 

The Main Return Pipe. — The nearly horizontal pipe 




Fig. 5. 

on the floor, or thereabouts, of the cellar, for carrying 
the condensed water back to the boiler. 

The Steam Riser. — The vertical pipe which carries 
the steam from the main distributing pipe to the radi- 
ator connectioDS. 

Die Return Riser. — The pipe which carries the con- 



GRAVITY-GIBGULATING APPARATUS. 7 

densed water from the radiators down to the main 
return pipes. 

The Steam-Riser Connection. — The pipe which joins 
the main distributing pipe and steam riser. 

The Return- Riser Connection. — The pipe which coii 
nects the return riser with the main return pipe on the 
floor. 

The Steam-Riser Relief, — The pipe which connects 
the bottom of the steam riser with a T in the bottom 
of the return-riser connection or with the main return 
pipe, generally below the water-line. It carries the 
water which runs down the steam riser into the 
return-riser connection or main return pipe. 

Main Relief Pipes. — Connections between the main 
steam and return pipes, to throw the water carried 
from the boiler, and that condensed in the main 
steam-pipe, into the return main, also employed as an 
equalizer of pressure in the system. 

Radiator Connections. — The pipes which run from 
the risers to the radiators, both steam and return, 
usually no longer than is necessary to get sufficient 
spring for the expansion of the risers. 

Rising Lines. — The steam and return risers take: 
together. 

A Relay. — The jumping up of a main steam-pipe, 
with a main relief at the lower corner. This is to 
admit of keeping the main steam-pipe near the line of 
the risers and ceiling, and above the water-line, when 
the main lines are long. 

Pitch— Is the inclination given to any pipe, and in 
the steam mains of a low-pressure or gravity appara- 
tus, it should be down and away from the boiler so 
steam and water will always flow together (except in 



8 



STEAM HEATING FOR BUILDINGS. 



System No. 5), and, if possible, tlie pitcli should be 
toward the boiler in the main return. This is to have 
the water and the steam run in the same direction 
through the pipes, so as to prevent one source of 
noise in an apparatus. 

Water-Line. — This is the term given to the general 
level of the water in the boiler and throughout the 
apparatus. In some cases, where the boilers are at a 
distance, or in a subcellar, and the fitter wishes to gain 




the advantages of having return mains and their return 
pipes and reliefs coming together heloiv tvater, he makes 
an artificial water-line by raising the main return pipes 
higher than his connections before he drops to the 
boiler. It is also necessary to bring a relief, a, from the 
main steam-pipe to this raised part of the return to 



aBAVITY-CIRCULATING APPARATUS. 



9 



prevent siphoning into the boiler. Fig. 6 shows how 
this shouki be done. 

It frequently happens in buildings where the line of 
the floor is below the water-line, that there are good 
reasons for not running the return pipe on the floor, 
when a modification of what is shown in Fig. 6 may 
be used ; the return pipe being hung from the same 
hangers as the steam-main, and immediately below it, 
but raised about as shown before being dropped to 
the floor at the first available position. Still another 






Fig. 7. 



modification is to trap each return riser with an in- 
verted water siphon by running the return riser some 
distance below the main return pipe, then rising and 
connecting with it, as shown in Fig. 7. When any of 
these means have to be resorted to, it would be well 
to have a pet-cock at their lowest points to draw the 



10 STEAM HEATING FOR BUILDINGS. 

water from them in cold weather should they not 
be in constant use, as these water-traps may 
freeze. 

The loop shown at the bottoms of the rising-lines in 
Fig. 7 should be used only with '^two-pipe work/' as 
shown. 

With single or ^'one-pipe work'' the loops are a detri- 
ment. 

They are used in two-pipe work to secure a slight 
difference of pressure between the steam rising-line and 
the perpendicular return pipe, so as to force the steam 
air and water in a continuous direction and through 
the coils or radiators, but the loop can do no good in 
single-pipe work, or in single-pipe rising-lines with 
double, nor is a '' water-loop '^ at the extremity of a 
double main of any service when there are nothing 
but single-pipe rising-lines. Of course the ends of a 
double main should be connected, that is, the steam 
with the return, but the water-seal does no good, unless 
to force a circulation in a double rising-line or through 
a first-floor radiator, with a steam and return pipe — a 
"two-pipe radiator." 

Some advantage may be found in putting a water- 
loop in a double overhead main, with double-pipe rising- 
lines, as shown in Fig. 7, but care must be taken that 
the air cannot be ''trapped" in the return-pipe, as it 
will be between the water-line at the boiler and the 
water in the seals. There must be some way of getting 
this air out freely. An automatic air- valve at the 
highest point in the return may do. It is better, how- 
ever^ to have a free connection with the main, so the air 



GRAVITY-CIRCULATIXG APPARATUS. 11 

will disappear into the general system and be drawn 
off at the radiator air-cocks. 

The 'trapping'' of air in a return pipe is a very 
serious matter, and it is not generally understood by 
the fitter, and rarely looked for by one who is called in 
to tell why some work will not circulate properly. 
The writer did not fully appreciate its importance in 
o^ erhead mains until quite recently. The air was 
caught in such a manner in a dry return pipe as to 
hold up a section of a large building. 

HOW A BUILDING WITH WOODEN FLOORS IS PIPED. 

The steam-fitter should commence his work in a 
new building at an early period of its construction ; 
and architects and parties paying for the work should 
see that the contract for steam heating be let when 
the mason and carpenter work is let. 

The risers are the first work done in a new building 
constructed in the ordinary way. The architect 
should see that the builder and steam-fitter have an 
understanding at the commencement of the work and 
that the former leaves the proper recesses in the walls 
exactly where the steam-fitter requires them with 
proper regard to the strength of the walls. This will 
save much work to the fitter, and prevent the mutila- 
tion of the walls, and be no expense to the mason. 

When the walls are up, the joists in their places^ 
and the roof-boards or roof on, the steam-fitter should 
then put up his risers. 

If the building has not more than three or four 
floors to be heated, it will answer to rest the risers on 



12 STEAM HEATING FOR BUILDINGS. 

a support at the bottom of tlie recess ; but in higher 
buildings the risers should be suspended by the 
middle, so that the expansion may be divided. By 
allowing the riser to go both up and down from the 
middle, the steam-fitter will be able to get along with 
shorter radiator connections, and will avoid the deep 
cutting of the floor joists in wooden floors. 

The steam-fitter should avoid, as much as possi- 
ble, taking many heaters from the same steam connec- 
tion on a floor, and if it be unavoidable, he should if 
possible bring his return connections into the return 
riser some distance apart ; or, he should run them 
separately down below the water-line, as it will pre- 
vent one heater from taking the air from the others or 
the return water from opposite directions meeting in 
the same fitting. When this cannot be done an 
enlargement of one size in the return piping when 
they come together should be provided so the oppos- 
ing currents of water will not appreciably affect each 
other. 

If the risers are on the side of the room, so that 
their outlets come between the joists, it is best to keep 
the T's about Jialf-iuay betioeen the laths and the flooring, 
as this admits of nippling up, and leaves room for cross- 
ing the pipes, if required, below the floor. But should 
the outlets come at the side of the joists, care must be 
taken that the T's come in the exact place to avoid the 
unnecessary cutting of beams. In a building with the 
risers resting on the bottom, and all the expansion 
upward, the top outlet must be the greatest distance 
below the top of the joist, but the top of the fitting 
must never come within less than J of an inch of the 



GRAVITY-CIRCULATING APPARATUS. 13 

floor wh«n the riser is expanded to its utmost ; so also 
with the rest of the T's, according to their distance 
from the bottom of the riser. The question of the 
expansion will be treated hereafter. 

With low-pressure steam, the steam risers should 
be large. The general practice with steam-heaters is 
to reduce one size of pipe for each floor. This rule is 
not arbitrary ; but as architects' specifications usually 
call for it there can be no objections, provided the 
piping is sufficiently large in diameter for its work. 

In System No. 1 the return riser is generally one 
size smaller than the steam riser, but it should never 
be smaller than f of an inch pipe. 

In System No 2, where many return risers are 
brought down in the same place, a 1-inch pipe for large 
heaters, and a |-inch pipe for small ones, are the sizes 
used generally. A |-inch pipe however will drain a 
100 square foot heater if there is no great length of 
horizontal pipe. 

When the risers are in place the outlets should be 
plugged up with pieces of pipe a foot or so in length, 
instead of the ordinary plug, as the latter is often diffi- 
cult to get out when the recess is covered and tL^ 
plastering done. 

The risers should then be tested with cold water to 
100 pounds per square inch. This will show if there 
are any cracked fittings or split pipe, and will save 
much time and annoyance when steam is gotten up. 

When automatic air-valves are to be used on the 
steam-heaters, coils or radiators, a |-inch pipe should 
be run in the riser recess, with an outlet at each floor 
to receiye the giir-yalve connection. The lower end of 



14 'STEAM HEATING FOR BUILDINGS. 

this air and vapor pipe should be taken to tlie nearest 
sink in the basement where any unusual waste of water 
or steam will be noticed by the engineer or janitor. 

At this stage of the work, and before the floors 
are laid, the radiator connections should be run and 
firmly fastened in their places, making due allowance 
for the thickness of the floor, the furring on the w^alls, 
for the plastering, and for the baseboard. The radi. 
ator connections are usually run 1 inch or IJ-inch 
for the steam connection, with a corresponding f or 
1 inch pipe for the return, according to the size of the 
heater ; 1 J- inch steam-pipe being enough for a direct 
radiator of 150 square feet of heating surface, at low 
pressure. 

When the radiators are threaded right-handed, the 
valves may be left-handed, to admit of connecting, by 
a right-and-left-hand nipple between the valve and 
radiator. When the valves are at opposite ends of the 
radiator, however, it is often difficult to use right and 
left nipples this way, unless there is considerable 
movement to the pipes under the floors, in which 
case either union valves must be used, or the right 
and left nipple must be between the lower end of the 
valve and the elbow under the floor. 

When both valves are at the same end of the radi- 
ator, it is better to have the right and left nipples 
between the valves and the radiator. With this 
arangement both valves of the radiator can be con- 
nected simultaneously, and the movement of the 
radiator will be in the direction of the valves. It also 
admits of the disconnection of a heater after simply 
closing the radiator valves. _^^ 



GRAVITY-CIRCULATING APPARATUS. 15 

When the radiators are to be connected by any of 
the foregoing methods, the connections can be 
fastened (but not confined at their ends), so they may 
come in their exact places through the floors. The 
free ends of the connections should be closed with 
pieces of pipe long enough to come above the floors 
when the latter are laid. The air-pipe should also be 
run at the same time and brought through the floor 
In close proximity to the position the air-valve will 
occupy on the heater. 

At this stage of the work the steam-fitter usually 
waits until the floors are laid, plastering done, par- 
titions set and the basement graded. 

Steam J/ams.— Nearly all the success of the ap- 
paratus depends on its steam mains, their sizes and how 
they are run. 

A heating apparatus has never yet been spoiled by hav- 
ing its steam mains large ; still there should be a limit 
to their size, to prevent unnecessary expense and to 
keep the condensation and radiation of the distribut- 
ing pipes at minimum consistent with the actual 
requiremnets of the heating surfaces. 

The size of steam mains for heating apparatus ,of 
course, depends on the pressure of steam to be used, 
the distance it is to be carried, the temperature of the 
exposure of the heating surfaces and their extent, etc. 
As it is not my intention here to speak of steam 
used expansively, I shall endeavor to give sizes only 
for the direct return, or gravity-circulation apparatus. 
The sizes of steam mains and other piping for heating 
apparatus of course depend on the pressure of the 
steam to be used, the distance it is to be carried, the 



16 STEAM HEATING FOR BUILDINGS. 

temperature and the exposure of the heating appara- 
tus and their extent ; and this applies equally to all 
kinds of heating apparatus whether high pressure or 
low pressure. It is not my intention however to speak 
here of steam used expansively, but to give sizes, for 
the direct return of the water of the gravity circulat- 
ing apparatus just described, leaving the sizes of 
mains for steam used expansively to a later chapter in 
the book. 

A well-arranged gravity circulation should be made 
to work at any pressure; for with its heating surface 
properly proportioned it can be made to at least partly 
meet the exigencies of fall, winter, or spring weather, 
by simply carrying a pressure suitable to the occasion. 
To have the water of condensation return directly 
into the boiler, under all conditions of pressure, the 
main pipes must be large enough to maintain the pressure 
of the boiler to within half pound, in every part of the appa- 
ratus. The water-line of the boiler should be not less 
than 4 feet from the bottom of the horizontal distrib. 
uting mains at their lowest part, and that distance will 
only answer in short mains, such as those used in the 
generality of city business buildings and blocks. lu 
large public buildings and others, having their boilers 
in out-houses, the difference between the boiler line 
and the mains should be all it is possible to make it. 

A main steam pipe should not decrease in size 
according to the area of its branches, but very much 
slower, and should be rated by the heating surface and 
the distance steam is to be carried. Neither should 
the main at the boiler be equal to the aggregate size 
of all its branches — an ex.prepsiori very much in vogue 



GRAVITY CIRCULATING APPARATUS. 17 

in specifications for steam heating — or the mains may 
be unnecessarily large at the boiler. 

Mains which have given the best results leave the 
boiler of sufficient size (calculated from practical 
results), and they are reduced slowly, being pro- 
portionally larger the farther they have to carry 
steam, the friction of the steam as it passes through 
the pipes being the important element for considera- 
tion. 

Were there no friction, there would be no loss of 
pressure, and the water-line would be the same no 
matter how far it was from the boiler. The diameter 
of the pipe and the quantity of steam passed through 
it determ^ines the friction. If the friction in a 1-inch 
pipe, 100 feet long, is represented by 16, the friction 
in 50 feet of it will be 8, and in 200 feet of it it 
will be 32. If the same quantity of steam has to pass 
through a 2-inch pipe, the friction for 100 feet will 
be about 3, for 50 feet 1.5, and for 200 feet 6. 

The friction rules governing this question are: (1) 
friction increases directly as the length of the pipe; (2) 
velocities remaining equal, friction varies about as the 
2.5 power of the diameter of the pipe. 

The area of the cross section of a 1-inch steam-pipe 
is generally taken as unity in the rating of steam-pipes 
for heating apparatus, and the area of a 1-inch pipe 
(in the main at the boiler) to each 100 square feet of 
heating surface is considered the limit of good ordinary 
practice. It has been the writer's ready method for 
years, and is deduced from the size of the mains and 



18 STEAM HEATING FOR BUILDINGS. 

heating surfaces of some of the best heated buildings 
in the United States, and forms a safe approximation 
when closer methods are not at hand. The method of 
determining the size of steam mains for gravity 
apparatus bj other methods will be treated in another 
chapter. 

When the main steam-pipe leaves the boiler, it 
should, if possible, be carried high at once, and have 
the stop-valve at the highest part of the pipe, so that 
condensed water cannot lodge at either side of it when 
shut. This will prevent cracking at this part of the 
pipes when the valve is opened. If this arrangement 
cannot be carried out, and the valve has to be nippled 
on the dome of the boiler, or if there are several boil- 
ers, and they have to be made interchangeable with 
regard to their use, there should be a relief of large 
size in the main, just outside the valves. 

It is well to mention here that a relief which 
leaves the steam-pipe must be brought into the return 
pipe in a position corresponding exactly to where it 
leaves the main ; that is, when it comes from the out- 
side of the main stop-valve, it should be taken to the 
outside of the main return valve. Otherwise, if an 
attempt is made to shut off, and both valves are closed, 
the water will " hack up " and fill the apparatus. So, 
also, with all branches, risers or connections. If there 
is a valve in the steam part, there must also be one in 
the return parts corresponding thereto, and reliefs 
must leave the steam-pipe and enter the return on 
corresponding sides of the respective valves. 

From the highest point the main steam-pipe 
should drop slowly, as it recedes from the boiler {\ 
inch to 10 feet being a fair pitch), that the course 



GRAVITY-CIRCULATING APPARATUS. 19 

of the steam and the water may be in the same 
direction. 

A main steam-pipe should not run very close to the 
wall up which the risers go. There should be room 
enough for a riser connection (2 or 3 feet), and when 
the mains are long, and the expansion great, the dis- 
tance should be increased. 

The T's in the main, for the riser connections, 
are better turned up than sidewise, as by nippling an 
elbow to them you can get any desired angle, and 
should the measurement for the main be a little incor- 
rect it will assist in making connections. This ar. 
rangement also makes a good expansion joint, if the 
mains have much travel. 

Where the pipe reduces in size, it is well to put a 
relief in the lower side of the reducing fitting, as the 

water that is pocketed there, 

n by the large pipe pitching in 

D the direction of the smaller 



I 



:^^ 



Pi s one, may be the cause of 

cracking and noise in the 
pipe. Some steam fitters use an eccentric fitting in re 
ducing which brings the bottom of the pipes on V. 
same line and makes good work. See Fig. 8. 

When it is necessary to have stop valves to the 
risers, the steam-fitter often places them in the riser 
connections, with a valve also in the riser relief. This 
arrangement requires three valves, and also stops the 
local circulation and equalization of pressure between 
the main steam pipe and return pipe when the valves 
are closed. Fig. 9 shows this method. 

It is better to use only two valves, when it can be 
done, one to the steam and one to the return riser, 



20 



STEAM BEATING FOR BUILDINGS. 



and place them a fewiuclies up the riser, above the 
riser connection, which brings them also above the 
steam-riser relief, saving a valve and lessening the 
chances for noise in the pipe. It allows the local cir- 
culation to go on between steam and return pipe 
when the valves are closed. This is shown in Eig. 10. 




Fig. 9. 



In System No. 2, where the returns are carried 
down separately, and collected together below the 
water-line, the return valve siiould be below all sucli 
connections, and the steam-riser relief should have a 
separate connection with the main return, and ha v. 



ORAVITY-CIRCULATINQ APPABATV6. 



21 



no valve. This is sliown in Fig. 11. Straightway 
valves are best for risers. 

Tiie extreme end of a steam main should be con- 
nected by a relief with the main return, being in fact, a 
continuation of the main down and into the return. 




Fig. lo. 

Stop-valves in main steam-pipes are either globe, 
angle, or straightaway. When a globe valve is used» 
it should be turned with its stem nearly horizontal, as 
shown in Fig. 12. The reason for this is obvious, when 
we consider that the water of condensation in any pipe 
runs along the bottom of it. When a globe valve is 
turned up, as in Fig. 13, the water in the pipe has to half 



22 



STEAM HEATING FOR BUILDINGS. 



fill it before it flows over the valve seat to pass along 
in tlie pipe. But, when the valve is on its side, it is 
different, for then the side of the ofening of the valve seat 
is as low as the bottom of the pipe. 

Neither should the stem of any valve be quite hori- 
zontal when it can be avoided. It should be raised 

1 2 3 








Fig. II. 



enough (10 degrees) to prevent water from collecting 
in the threads of the nut and stem, and being forced 
out by the pressure of the steam through the stuff- 



ORAVITY-CmCULATmO APPARATUS. 



23 



jng-box, wliicli makes a constant dropping of water, 
that it is almost impossible to hold with ordinary 
packing. But with dry steam it can be held. 

Globe or angle valves should be so turned in a heat- 
ing apparatus that by simply closing the valve to he 




Fig. 12. 

'packed, and its corresponding valve in the return, or 
vice versa, and waiting for the steam to cool down, the 
stuffing-box or gland can be removed without the 
escape of steam. To do this it is necessary to have 
the pressure side of every pair of valves turned toward 




Fig. 13- 

the boiler. By the pressure side of a valve is meant 
the under side of the disk. 

Main Return Pipes. — In small apparatus (up to 
3-inch steam-pipe) they are usually run on one or two 
sizes smaller than the corresponding steam-pipe. 

In returns which are below the water-line, or are 
trapped to give them an artificial water-line, and' con- 



24 STEAM HEATING FOR BUILDmOS. 

sequently always full of water, smaller piping will 
generally do, but good practice has placed it at not 
less than one quarter of the area of the steam-pipe, for 
all conditions, for apparatus with larger than a 3-inch 
steam-pipe. 

In apparatus with less than 3- inch pipe, the return 
is usually only one size smaller than the steam-pipe, 
that it may have a practical magnitude, and thus avoid 
the possibility of getting it stopped with the dirt or 
sediment carried to an elbow with the current of the 
water. 

In dry returns — i. e., which have no water-line — 
there are local steam currents, often going in contrary- 
directions, the water gravitating toward the boiler, and 
the steam flowing to the heaters and alway in the 
direction of least resistance. This style of return is 
now much used in exhaust steam heating and in cases 
where there is no basement it cannot always be 
avoided even in gravity work. One-half the area of 
the steam-pipe has been found, in practice, to give 
good results in dry return pipes. 

Check-valves are generally used in return pipes 
where they enter the boiler. Some steam-heaters 
leave them out on account of the back pressure they 
cause to the return water ; but the practice is not 
to be recommended when two or more boilers are 
connected, as an inequality in draught, or the cleaning 
of a fire will make a small difference of pressure 
between boilers, causing the water to run from one 
boiler to another through the return pipes. 

Check-valves of large area in the opening, with a 
small bearing on the seat, can be made that will not 
give more than one eighth of a pound back pressure. 



QRAVITT-GIRGULATINQ APPARATUS. 25 

or swinging clieck-valves can be used tliat practically 
cause no resistance to the flow of water. 

The diameter of the return pipe is sometimes re- 
duced where it enters the boiler, but it must only be 
done with caution and by one who is acquainted with 
the subject, as the resistance to the flow of the water 
increases much more rapidly than the decrease of dia- 
meter of the pipe. 

Extra strong pipe and fittings should be used in all 
returns and feed-pipes, from where they are tapped 
into the boiler, to outside the brickwork ; and when 
they are exposed to the action of the fire it is well to 
cover them with a " slip tube " made of a larger size, 
ordinary steam pi^e. 

A circulating pipe is sometimes used in connection 
with a blow-off pipe or a return pipe, starting from 
a point inside the valve and connecting into the rear 
boiler head above the tube-line, but below the water- 
line. 

This is shown in Fig. 14. 7? is the regular blow-off 
pipe, or it may be the return pipe. S shows the posi- 
tion of the stop- valve and C is the circulating pipe; 
which should have a valve in it. C 1 shows that the 
same may be closed when blowing off or to force a cir- 
culation should a stoppage be suspected in the pipe R. 

A circulating pipe will prevent the burning out of 
the blow-off pipe, so usual inside the boiler walls. 



26 



STEAM HEATING FOR BUILDINGS. 




CHAPTER II. 



RADIATORS AND HEATING SURFACES. 



All radiators, box coils, flat coils, plate or pipe 
surfaces, arranged to warm tlie air of buildings, are 
heating surfaces. 

The vertical wrouglit-iron tube radiator, and tlie 
cast-iron sectional type of vertical loop radiators, are 

now the accepted 



>ffl/?>>/^ 



y 




T. 



A 



Fig- 15. 



of first-class heaters, 
and nearly all man- 
ufacturers have their 
own peculiar style, 
with varying results 
as to efficiency. The 
steam-fitter or pur- 
chaser should use 
great caution in the 
selection of radia- 
tors. 



The common return bend radiator, Fig. 15, is of old 
style, is not patented, and its construction is simple ; 
a base of cast-iron, A, being simply a box, without dia- 
phragms, with the upper side full of holes about 2^ 
inches from centre to centre, tapped right-handed ; a 

27 



28 



STEAM HEATING FOR BUILDINGS. 




Fig. 1 6. 



Fig. I 6a. 



pipe, B, for every hole, 2 feet 6 inches or 3 feet long, 
threaded right and left handed, and half as many 

return bends, C, as 



r^\ 



there are pij^es tapped 
left handed. 

The comroon manner 
of putting these heaters 
together is to catch the 
right-handed thread of 
two pipes one turn in 
the base, then apply 
the bend to the upper 
and left threads of the 
same two pipes, and 
screw them up, simul- 
taneously with a pair 
of fiat-backed tongs on 

each pipe, while a second person holds the bend with 

a wrench made for the purpose. 

The sectional cast-iron radiators are of many types, 

the principal feature of which is a cast-iron loop or 

section, two modifica- 
tions of which are 

shown in Figs. 16 and 

16a. These sections are 

joined together at the 

lower ends by screwed 

nipples or by compound 

tape nipples, and are 

usually reinforced by a 

long bolt running from 

end to end near the 

top, as shown in Fig. 17. Fig. 17., 




RADIATORS AND HEATING SURFACES. 29 

There are a great many designs of this cast-iron 
sectional radiator, and the principal difference that 
exists between them is in ornamentation alone, if we 
except the methods of joining the sections together. 
There are modifications also of the surface of the 
radiators, the object being to increase the condensa- 
tion by the nature and form of the surface. Some are 
entirely plain surface, except ornamentation, and the 
vertical lines are straight ; others have extended sur- 
faces or jDarfcially extended surfaces, so that when the 
sections are put together they form vertical air pipes 
between the sections ; others also have pin prejections 
to increase their surface area, the object always being 
to increase the efficiency. 

Experiment has not always demonstrated that an 
increase of surface is an increase of efficiency, in that 
it sometimes shows the reverse, and the radiators that 
give the greatest efficiency per unit of surface are 
those of considerable distance between the loops, 
and have loops of a rather plain design. The effort of 
the manufacturer to-day is to increase the efficiency 
without increasing the floor space occupied by the 
radiator, and, if possible, not to increase its weight 
per unit of efficiency. This results in many forms, 
some radiators being long and narrow, others short 
and wide, 

I will here explain the action of steam entering 
a radiator, as nearly all tlie patents on the so-called 
positive circulating radiators are to facilitate the ex- 
pulsion of the air and the admission of steam. 

The general impression among steam fitters is that 
when steam enters a radiator the air is forced up and 
confined in the tops of the pipes, which is the fact 



30 STEAM HEATIXG FOR BUILDINGS. 

wlien tlie pipe is single, of small diameter, closed at 
the top, and without any of the usual means to get it 
dcwn, although the air at the same density is about 
twice as heavy as the steam, and apparently should 
fall without assistance. 

When two pipes are connected at the top with a 
bend, or when there is an inside circulating pipe, or a 
diaphragm of sheet-iron slipped into the heating pipe, 
the air immediately gives way and falls in the pipes 
nearest the inlet. Should there be no air-Talve on 
the radiator, the air will be crowded to the return end 
of the radiator, and should the system be a gravity 
circulation, without an outlet to the atmosphere, it 
will remain in the radiator, impairing its efficiency and 
often deceiving the novice, as it in time heats somewhat 
by mixture and contact with the steam. When there is 
a thumb-cock or air-valve on the radiator, usually on 
the furthermost pipe from the inlet, the air can be 
withdrawn from the heater, when the result is quite 
different, the radiator becoming steam hot over its 
whole surface. In a radiator of good construction 
the action is direct, the pipes, loops or sections heat 
consecutively, excepting, perhaps, the one the air- 
valve is on, and a few near it, which sometimes heat 
ahead of their order, on account of the draught of the 
air-valve. Thus, when the steam enters a well-con- 
structed radiator the air falls to the base and is driven 
out at the air valve. 

In Plate I., at the front of the book, are shown 
some old ideas in regard to radiators, and the belief 
held about the necessity of making them positive in 
action. In No. 1 the pipe D is carried down nearly 
to the bottom of the base, the idea being to facili- 



RADIATORS AND HEATING SURFACES. 31 

tate the circulation of steam and the expulsion of the 
air. 

No. 2 shows a device (patented) for making a return- 
bend radiator positive. The pockets A A, filling with 
condensed water, makes a seal which at times prevents 
the flow of steam along the base and forces it in a con- 
dnaous stream throagh the pipes (see arrows in cut). 

Nos. 3 and 4 show^ cross-section of modifications of 
positive return-bend radiators. No. 3 can be used as 
a vertical radiator only, but No. 4 can be used in any 
position from perpendicular to horizontal, as seen at 
Nos. 5 and 6. 

Single-tube radiators, welded or closed at the top 
with a cap, with an inside circulating device, were also 
much used ; some of them compared favorably with 
the return-bend radiator, but were slower in heating. 

No. 7 shows the first radiator put on the market, 
and one which has survived and is in use at the present 
time. A is the cast-iron base, B the welded tube, and 
G the septum of wrought-iron slipped inside the tube 
and projecting an inch into the base. This heater 
depends on the gravity of the air for a circulation."^ 

No. 8 shows another heater of this class which is 
positive in its action. A, cast-iron base ; B, diaphragm 
cast in base ; C, welded tube ; D, inside tube, open 
top and bottom, and screwed into the diaphragm. The 
action of the steam can be seen by the arrows. 

No. 9 shows a fire-bent tube radiator positive in its 
action. 

*This was the original **Nason" radiator. An improved form of 
this radiator (Fig. i8, on next page) is now on the market, in which the 
bases of the double rows and all wider are perforated at the lower end of 
every tube, to provide for a more free circulation of the air. 



32 STEAM HEATING FOR BUILDL\G3. 

23. Cast-iron radiators are of two kinds, plane and 
extended surfaces. 

Plane surfaces, as the trade understands them, may 
be either flat, round, or corrugated, provided the 
coring, or inside surface of the iron, corresponds and 
follows the indentations of the outside, as in No. 10, 
Plate I., and in all wrought-iron heaters. Extended 



Fig. 1 8. 

surface is understood when the outside surface of the 
heater is finned, corrugated or serrated, with the 
inside straight, as in No. 11, Plate I. 

For direct radiation, where the heater is placed in 
the room, there is little or nothing gained by having 
the surface of the heater extended, and a steam-fitter, 
in calculating the extent of his heating surfaces, 



RADIATORS AND HEATING SURFACES. 



33 



should not take into consideration the whole outside 
surface of such a heater unless he gives it some value 
less than unity, the unit being a square foot average of 
plane surface. 

For indirect heating the result, with extended sur- 
faces, is different as compared with shallow plane surface 
coils, where the air cannot stay long enough in contact 
with them to get thoroughly warmed, but presses into 
the room without hindrance. In this case the ex- 
tended surface gives a better result, though not because 
a square foot of the surface can transmit as much heat 
in the same time, but because it hinders the direct 
passage of the air, 
breaking it up and 
holding it longer in 
contact with the hot 
surface. • 

The cast-iron verti- 
cal loop or sectional 
radiator is a quick 
heater, the large size 
of the chambers facili- 
tating the expulsion of 
the air. 

Fig. 19 shows the " Bundy " cast-iron loop radiator. 
It is a cast-iron base with air apertures through its 
bottom, and the pipes are double tubes of diam'uul 
shaped section cast in one loop and joined to the base 
by a single thread.* 




Big. 19. 



* The writer with his own hands made the experimental Bundy radiator 
in the shop of Mr. Chas. Gregg, in 62 and 64 Gold Street, New York 
City, in 1869. 



It was the first cast-iron loop radiator. 



34 



STEAM HEATING FOR BUILDINGS. 



Fig. 20 is tlie " Reed " cast iron loop radiator. The 
bases are apertured for the passage of the air, and 




Fig. 20. 

the loops are U-shaped tubes fastened at each extrem- 
ity to the base by the assistance of copper ferrules, 
into which the loop is forced by pressure. The bends 




Fig. 21. 

of the loops, at the top, interlock and are confined by 
a rod to prevent disturbance in handling. 

Fig. 21 shows the old box coil, the primitive form 
of an indirect radiator. 



RADIATORS AND HEATING SURFACES. 



35 



Fig. 22 showed the first extended surface radiator 
for indirect work. It is known as the " Gold " pin 
radiator, each section, for steam use, containing nomi- 
nally 10 square feet of heating surface. I show these 
two indirect radiators here as the box coil is the rep- 
resentative of the plain surface indirect radiator, and 
the Gold pin the representative of the extended sur- 
face radiator. They are both obsolete now, but many 
modifications of the ''pin" indirect radiator are now on 
the market. 




Fig. 22. 



Fig. 21a shows a coil of secondary surface known 
as " Gold's compound coil surface," and which was 
used for indirect heating, either as a steam coil or as 
a hot- water coil. It was also made into direct heaters 
in the form of one-inch vertical pipe radiators covered 
with the secondary surface, and inclosed within a 
sheet-iron case, with a register in the top to control 
the heat. 

Fig. 21b shows an inch pipe covered with this 
surface, which is No. 14 square wire in the helical 
form, one pound being wrapped on each lineal foot of 
pipe. It increases the efficiency of the one-inch 



36 



STEAM HEATING FOR BUILDINGS. 



horizontal pipe in condensing power full three times 
when made into indirect coils and properly boxed, and 




Fig. 2 1 A. 



in vertical radiators of moderate height the efficiency 

is about double what it would be for plain pipe. They 
are now obsolete and are shown for the ideas they 
contain. 




Fig. 2IB. 



Fig. 21c shows the old ''Gold" flat radiator. It 
was the earUest form of sheet-iron radiator and was 



RADIATORS AND HEATING SURFACES, 37 




38 



STEAM HEATING FOR BUILDINGS. 



first used in private house work in New Haven^ Conn., 
very early in the nineteenth century. These radiators 
are even now found occasionahy in old private houses. 
They are made of Russia iron, the edges being seamed 
over on a strip of wood. The daulking is formed by a 
depression in the outer sheet, fastened with washers 
and rivets and the valve is attached by means of a red 
lead putty joint. The air- valve was always placed at 
^he upper corner opposite the inlet- valve end. 




Fig. 2 id. 



Of course it is now known that the air-valve should 
be near the bottom of the radiator, since the density 
of air is greater than that of steam. A cold lower 
corner was therefore nearly always apparent with the 
air-valve placed as shown. These radiators can be 
used only with the very lowest of pressures, about 
one half pound per square inch above the atmosphere. 

Fig. 21d shows a modern sheet-iron radiator. These 
radiators are made of galvanized sheet iron and they 



RADIATORS AND HEATING SURFACES. 



39 



resemble the standard cast-iron radiators, except that 
they are hghter both in weight and in appearance 
and occupy less floor space for equal heating sur- 
faces. 

The process by which these radiators are manufac- 
tured is probably the most complete and unique in 
sheet-iron stamping and drawing, and to Mr. Kinnear 
is due the credit of this novel industry. These 
radiators are regalvanized inside and outside in the 
process of manufacture, so that all the seams are 
thoroughly sweated. The radiators will stand com- 
paratively high pressures of steam and they are made 
for hot water as well as steam. 

They are often electroplated for very fine work. 

The figures, 21c?, show respectively the close and 
+he open form of the radiator. 

inch between the sides. They are used in a one-pipe 
apparrtus and are occasionally seen in old buildings. 

Coils are always made of wrought -iron steam- 
pipe and fittings, and though not considered very 
ornamental, are first-class heaters, and give a high 
efficiency of condensation per unit of surface. 






Q 



m 



m 



^ 



% 



Fig. 23. 



Fig. 23 show a flat coil, which is a continuous pipe, 
connected with return bends at the ends, and strapped 
with flat iron, or supported on ornamental brackets. 
It is a very positive heater. 



40 STEAM HEATING FOR BUILDINGS. 

Fig. 24 shows a miter or wall coil. It is composed 

A 



JZL 



n 



±r 



r 



:d?T 



F, 






Fig. 24. 






r 



of headers or manifold, A A ; steam-pipes, B ; elbows, 
C ; and hook plates or rosettes, D. 

There are many modifications of this coil, and they 
are usually long 20 to 30 feet. One indispensable 
point in the making of this coil is it must turn a corner 
of the room, or miter up on the wall as shown. The 
pieces from the elbows to the upper header are called 
spring pieces ; they are screwed in right and left, and 
are the last of the coil to be put together. 

If a coil is put together, straight between two head- 
ers, as seen at Fig. 25, it will be like Fig. 26 when 
heated, and cannot be kept tight for a single day ; the 



JZL 



Z*T 



1^ 



Fig. 25. 



n 



T!T 



■ffl- 



expansion of the first pipe to heat, being a powerful 
purchase to force the headers asunder, and when it 



RADIATORS AND HEATING SURFACES. 41 

cannot do so it will spring tlie long pipes out of the 
hook plates or force the pipe to strip its own thread. 
The modification of the wall coil, shown in Fig. 24 is 
that used when there is no chance to turn a square 
corner of the room. A miter is then made in the 





Fig. 26. 

manner shown. When advantage can be taken of the 
corner of the room, however, it is better to turn a 
right angle on a horizontal plane, and in this way let 
the expansion of pipes from both directions be forced 
into the corner. The supports at the corner should 
be placed so that the hook plates of the short side of 
the coil will be as far as possible from the corner, and 
the hook plates and the long side very near the cor- 
ner. This will allow for the movement of the long 
pipe of the coil, as it expands to move towards the 
corner by slipping through its own hook plate, allow- 
ing all the pipes to compensate and equalize on their 
own supports without undue strain, and at the same 
time providing a support very near the corner of the 
coil, which, of course, is necessary to maintain the 
pipes in their proper alignment ; a corner being more 
apt to hang down than a straight run of pipe. The 
movement of the short part of the coil being small, it 
is easily compensated, so that if the support near the 
long pipe is but one foot from the corner, there would 



42 STEAM HEATING FOR BUILDINGS. 

be no trouble iu taking care of the expansion of five 
or six feet of pipe should the spring piece (short part 
of the coil) have that length. 

There are many other modifications of the wall coil, 
the particulars of which it is not necessary to enter 
into here. 



CHAPTER III. 

CLASSES OF RADIATION. 

Heating surfaces are divided into three classes : 
1st, direct radiation ; 2d, indirect radiation ; and 3d, 
direct-indirect radiation. 

Direct radiating surfaces embrace all heaters 
placed within a room or building to warm the air, and 
are not directly connected with a system of ventila- 
tion. 

The best place within a room to place a single radi- 
ator, is where the air is cooled — namely, before or 
under the windows, or on the outside walls. When 
the heater is a vertical tube radiator, or a short coil, 
which can occupy only the space of one window, and 
when, as often occurs in corner rooms, there are three 
windows, the riser should be so placed as to bring the 
line of radiators in front of and under the window 
where they will do the most good — as the middle 
window. Or it is better still, when a small extra cost 
is not considered, to use two heaters, and place one 
in front of each of the extreme windows. 

When the room is large and has many windows, the 
heating surface, when composed of radiators, should 
be divided into as many parts as possible, and, per- 
37 43 



44 STEAM HEATING FOB BUILBIiTGS. 

haps, as there are windows ; or shoukl the owners or 
occupants object to so many windows being partly 
obstructed, divide into half as many parts, and dis- 
tribute accordingly. 

In schools or factories, or buildings with many win- 
dows, where children or persons cannot change their 
positions, but have to remain seated for several hours 
at a time, care must be taken that the heating surface 
is evenly distributed. A coil run the whole length 
of the outside wall is best, but if any kind of short 
heaters are used, every window, or at least every sec- 
ond window, should have its share of the heating sur- 
face. Should a window be left unprovided for, it will 
be found by experiment that a cold current of air 
will fall down in front of such window and flow along 
the floor in the direction of the nearest heaters. 

The natural movement of the air currents in a room 
with the outside atmosphere the coldest, are always 
down at the windows and outside walls, and up at the 
center of the room or rear waUs. This downward and 
cold current should be met by the heated and upward 
current from the radiator, and reversed and broken up 
as much as possible. 

Indirect radiation embraces all heating surfaces 
placed outside the rooms to be heated, and is usually 
•only used in connection with some system of ventila- 
tion. 

There are two distinct modifications of indirect radi- 
ation. One, where all the heating surface is placed in 
a chamber and the warmed air distributed through air 
ducts, and usually impelled by a fan in the inlet or 
cold air duct. The other, where the heating surface 



CLASSES OF RADIATION. 45 

is divided into many parts, and placed near the lower 
ends of vertical flues, leading to the rooms to be heated. 

The first of this class — namely, chamher-heat — has 
not always proved satisfactory unless the air is impelled 
with a fan, as it has been found that in windy weather 
it is almost impossible to force air to the side of a build- 
ing against which the wind blows, with natural air 
currents alone. With the proper fan, however, this 
method of heating has become the one almost entirely 
used for hospitals and schools and many pubUc build- 
ings. There are many modifications of it, but the scope 
of this book is too limited to show its many phases 
and general application to buildings. The second of 
this class — the individual indirect radiator — does very 
well for private houses. Of course, the warmth of the 
radiator and the weight (or relatively the want of 
weight) in the column of air in the vertical flue is the 
prime cause of motion. The ordinary method of in- 
direct radiation, is that of having a radiator at the 
base of a vertical flue, the cold air being taken directly 
from out of doors and delivered in the room through 
the warm air pipe and register. This method has 
always done well for private residences and where the 
quantity of air that carries heat into the room is ample 
for its ventilation, as in medium size rooms or oflSces 
where a very few persons only are occupied or engaged, 
It is a good system. 

The indirect heater is usually boxed, either in 
wood lined with tin or in sheet metal. The former is 
best when the cellar is to be kept cool, as there is a 
greater loss by radiation and conduction through metal 



46 STEAM HEATING FOR BUILDINGS. 

cases; otherwise metal is best, as it will not crack, and 
when put together with small bolts can be removed to 
make repairs without damage.- 

The vertical air ducts are usually rectangular tin or 
galvanized iron flues built into the wall when the 
building is going up. Sometimes, however, they are 
only plastered in the rough, and sometimes lined with 
tile, but the smooth metal lining with close joints gives 
much the best result in all cases, and in the case of 
outside walls it is necessary that the flue should be 
hned, as the passage of air and loss of heat through a 
masonry wall is very great; moisture also playing a 
considerable part in destroying the efficiency of the 
flue in damp weather. 

A 12''Xl2'' flue in a wall will deliver between 
10,000 and 15,000 cubic feet of air in an hour to a 
room on the second floor of an ordinary house, if it has 
easy bends and is not too much obstructed by the 
radiator or register, and about one-half that amount of 
air will be delivered under similar conditions to the first 
floor through a short flue or floor register. A good 
common rule is to make the first floor flue twice the 
area of the second floor flue. 

There should be a separate vertical air duct for 
every outlet or register. In branched vertical air ducts 
uniformity of dehvery is almost impossible. 

The heated air from one heater when taken to two or 
more vertical air ducts will generally be unsatisfactory. 

Inlet or cold air ducts are best when there is one 
for every coil or heater, in what may be called the 
private-house method; and its mouth, or outer end, 



CLASSES OF RADIATION. 47 

should, if possible, face the same way as the room to 
be heated. By this means, when the wind blows 
against that side of the house, its pressure is into the 
cold air duct, and materially assists the rarefied column 
of air in the vertical duct in forcing its way into the 
room or house. 

Often the steam-heater uses only one large branched 
cold air duct. This system may give trouble unless 
the trunk flue and branches are carefully proportioned. 

The steam-fitter should not undertake a job of 
indirect heating unless the building has been arranged 
especially for it, with some efficient system of flues, 
sufficient to change the entire air at least once in an 
hour. 

Frequently designers make no provision for drawing 
away the cold or depreciated air. Such rooms cannot 
be warmed satisfactory by indirect heating. When there 
is a chimney, the heated column of air in the vertical 
hot air flue is generally sufficient to force its way into 
the room in quantities sufficient to warm it, even though 
it may not ventilate it to any considerable extent. 
Of course there is always some ventilation when the 
air is the vehicle of the heat. 

An inexpensive good method to make foul air flues 
draw is to connect them all to a annular flue, around 
the boiler chimney flue. The designer should always 
keep this in mind. 

A good rule is to have the warm fresh air flues near 
the outside walls, but not in them, and if possible, 
they should discharge near or across the windows. 
Foul air flues should be in the inner walls, and have 



48 STEAM HEATING FOB BUILDINGS 

an opening near the floor and ceiling, with registers, to 
allow the occupant to use either or both, as he thinks 
proper. Usually the lower vent is without means of 
closing it. 

The velocity of the air in heating flues with only a 
natural draught, rarely reaches 8 feet per second, no 
matter what the condition; and 2 feet, 4 feet, and 5 
feet respectively, are fair averages of velocities for 
first, second, and third floors of a house. Of course 
when the doors of the rooms are shut and there is a 
systematic arrangement of vent flues to the top of the 
house, the velocity of the draught for the short heat 
flues is considerably increased, as under such condi- 
tions the combined effort of both heat and vent flue 
tends to accelerate the current of air in the warm air 
flue. 

Direct-indirect radiation embraces all heating sur- 
faces placed within, or partly within, the room to be 
warmed, in direct connection with some system of 
fresh air supply. 

Heaters of this class are usually placed on the out- 
side walls or under windows, following the same 
general rules as for direct radiation, excepting 
the clusters are of a special class, so as to prevent 
the cold air from passing through without being 
warmed. 

Fig. 27 is a favorite modification of this style of 
heating. It is a section of a room, showing the appa- 
ratus and the supposed action of the currents of air. 
A A, outside wall; B, partition waU; C, radiator; 
D, inlet flue; E, damper or valve; F, ventilating 



CLASSES OF RADIATION. 



49 



flue or foul air outlet ; G, fresli air mixing with tlie 

air of the room ; H, air of the room passing along the 




Fig. 27. 

floor to the heater ; /, a percentage of the air in the 
room passing off by the ventilator. 




Fig. 28. 

Fig. 28 is a modification of direct-indirect radiation 
Bot often met with, but where with good success some 



50 STEAM EEATINO FOR BUILDINGS. 

of the local heat is employed to exhaust or draw out 
the vitiated air of the room and draw in the fresh air. 
The arrows show the supposed general action of the 
air currents within such a room. ^ is a section of a 
radiator built with a sheet-iron flue, B^ between the 
tubes, and passing through a hole, cored in the base 
of the radiator which connects with the register in the 
floor, aud a foul air flue in the wall. This system 
might be used to advantage in schools where, a fan 
cannot be employed. 

Some of the radiant heat, etc., A, warms the sheet- 
iron flue, B, which in turn warms the air within it 
causing an acceleration of the current in the foul air 
flue, and consequently drawing an equal amount of 
fresh air in at the opening, C. 

In estimating heating surfaces, for direct-indirect 
heating, it is well to use about once and a half as much 
as would be used for direct radiation alone. 

There is this further distinction between the three 
systems of radiation : Direct radiation warms only the 
air of the room and maintains the heat. Indirect 
heating warms only the air that passes in, and cannot 
warm the same air twice, and consequently has to 
raise the temperature of all the air that passes, from 
the outside temperature to that necessary to main- 
tain the temperature of the room. Direct-indirect 
radiation warms part of the air of the room over again, 
and warms all the air admitted for ventilation, which 
latter can be varied to the point of shutting it all off 
and depending on direct radiation alone. 

With ordinary indirect radiation (no fan), the 
heating apparatus being steam, a building may be 
sufficiently ventilated ; but it frequently happens in 



CLASSES OF BADIATION. 51 

large rooms with very high ceilings, or large auditor- 
nms, as churches, schools, theaters, or assembly 
rooms of any kind, that they are not always satisfac- 
torily heated, as it is difficult to warm them by in- 
direct radiation alone, unless there are many registers 
placed before the windows, or the apparatus is sup- 
plemented by direct radiators, placed where there 
will be strong local currents. 

Heated air from a few large registers in a very large 
room goes directly to the ceiling, and fills the room 
from above, expelling the same amount of air through 
the ventilators. If the building had no windows, 
this would probably answer ; but as buildings have 
windows and outer walls, which cool the air rapidly, 
there will be a falling of air in front of the windows, 
etc., which has not been pressed down by the warm 
air above, but has fallen of its own gravity, by losing 
its heat from contact with the cooling surfaces of the 
building. These downward currents, having nothing 
to neutralize them, pass over the heads and shoulders 
of the sitters and go cold along the floor on their way 
to the ventilator, or to an ascending current of warm 
air, caused by the heat given off from the bodies and 
lungs of the audience or any other cause. 

This is w^hy people in churches and theaters suffer 
from cold backs and feet, and sometimes have a cold 
current on their heads, which makes them certain 
" the window is open a little ; " though a thermometer 
near by marks 70 degrees, as the thermometer is prob. 
ably not in the cold current and will not take note of 
draughts anyway. 

If a building must be heated entirely by indirect 
radiation, it is well to use as many heat registers as 



52 



STEAM HEATING FOR BUILDINGS. 



possible, aud place them in front oi the windows, or 
where a cold current is likelj to come down. 

Usually in office rooms, and ordinary rooms in resi- 
dences, one register in the coldest part of the room 
can be made to answer ; but if the room is large, with 
many windows, more sliould be used. 

Figs. 29 and 30, perspective elevation and section 
respectively, of one of the indirect radiators as arranged 
in the Cambridge Hospital, in the early days of the 
'^switch dampers/' and show the arrangement of the 
air-inlet pipes A, mixing valve D, hot-air pipe i7, and 
register-box R, within the wards, as well as a section 




Fig. 29. 



of the vent-ducts, V A, with the vent-outlet under each 
bed(F). 

The coil casings or air boxes are made of No. 22 
galvanized iron, with flanged corners, and the steam- 
radiator is suspended midway in the case, as seen in 
Fig. 30. The indirect heaters are " pin " sections, 
centre connection, eight sections being used to each 
hot-air box. The cold air enters through the 10-inch 
round pipe A, Fig. 29, and shown separated on cellar 
plan by the arrows, the mouth of which is protected 



CLASSES OF RADIATION. 



53 



bj a register-face and frame. As the air enters 
tiirougii A it can be made to pass either under and 
through or above the lieating-surfaces of the radiator 
bj means of a sliding damjjer, D, or the air-current 
may be divided by placing the damper in a nearly 
central position, allowing some of the air to pass each 




Fig 30. 



way, thereby regulating its temperature without re- 
ducing its volume. The upper end of this damper is 
connected by a chain with a pull-and-stop mechanism 
within the ward, so that the attendant can regulate 
the heat of the air without leaving the room. The 
apparatus is called a " mixing-valve." This modifica- 
tion was selected, as it embodied the ideas of Dr. 



54 STEAM HEATING FOR BUILDINGS. 

Wyman, a well-known writer on ventilation ; but more 
modern examples will be given elsewhere. 

It will be seen that the dampers in the cold air, 
inlets are not automatically regulated. They are 
sometimes so regulated to prevent the freezing of the 
coils ; but when the steam and return pipes are suffi- 
ciently large coils, are seldom frozen, for when steam 
is up they cannot freeze, and when steam is not up, 
there is no water in the coils to freeze, for it has sub- 
sided to the water line level, which should always be 
a safe distance below the coils. Only an apparatus 
with small diameter pipes and parts will freeze, unless 
the coil is too close to the water line, or partly below 
it. 

Indirect coils should never be shut off in very cold 
weather. If the room is not to be heated, close the 
registers and inlet ducts. The closing, or partly 
closing, of a valve, may freeze a coil, by interrupting 
the circulation. The closing of one valve and the 
leaving open of the other is sure to freeze a coil if ex- 
posed to sufficient cold, as in either case it will fill 
with water. This applies to all radiators. 

Fig. 31 shows a modern switch valve and arrange- 
ment of an indirect coil now usually applied to school 
rooms. The radiator is generally a large one, as it is 
usual and necessary to admit about one hundred 
thousand cubic feet of air per hour to a room that will 
contain fifty pupils. 

The register, therefore, has to have a large air area. 
In other words, it is not so necessary to have it deep 
as it is to have it cover a large surface, in order that 
abundant air can pass through it without material 



STEAM HEATING FOR BUILDINGS. 




Fig. 31 



[To face page 55. 



CLASSES OF RADIATION, 55 

resistance and rather low velocity. The flues, in like 
manner, have to be of ample area, 3. to 4 square feet 
generally being necessary for the average school room. 
The indirect radiators are built on I beams and enclosed 
in brick walls, though some times galvanized iron is 
used. Brick walls or expanded metal chambers of large 
size should be encouraged. They permit of inspection 
and changing. Cold air is admitted at the bottom of the 
chamber, where it may either pass upward through 
the radiator and through the switch " S " into the hot- 
air flue and thence to the register in the school room, 
or it may pass through the lower opening into the 
same flue when the switch valve " S " is closed. At 
" Q " on the wall in the school room is a quadrant 
operating a rod which works a lever that connects 
directly with the switch valve " S " by a chain. When 
the switch valve is in the position shown by the full 
lines, entirely warm air is passing to the school room. 
When the switch valve is in the position shown by the 
dotted lines, cold air only can pass into the school 
room, but when it is put in any intermediate position, 
cold air from below the radiator and warm air from 
above it meet and mix in the flue, and pass as tempered 
or "mixed" air into the school room. 

This is the usual method now of securing variations 
of temperature in the school rooms, without interfering 
with the quantity of air to be admitted in a given time. 
Details of construction are shown by the drawing. 



CHAPTEK IV. 

HEATING SURFACES OF BOILERS. 

The direct heating surface of a boiler (the fire 
box or crown sheet), has a value several times greater 
than the indirect surface (flue or tube surface), but 
the shape of the furnace, its size, and the angle of the 
heating surface, as well as the length, size, and position 
of the flues, give a greater or less value to the indirect 
surface ; these values, of course, are only comparative. 

In constructing boilers for heating apparatus, an 
effort should be made to have the greatest possible 
amount of direct surface, with sufficient indirect surface 
to properly cool the gases of combustion. 

When furnaces are comparatively small, with a high 
rate of combustion, flue surfaces may be lengthened 
with beneficial results; but in a private house, with a 
self-feeding boiler (base burner) or one which has a 
deep furnace, constructed to hold six to eight, or even 
twelve hours' coal, and keep steam uninterruptedly 
for that time, a great part of the heating surface should 
be in a fire-box; the heat from the gases being com- 
paratively low tempered, and the amount passed in a 
given time small. 

It would be well to say that many writers on boilers 

56 



HEATING SURJ^ACES OF BOILERS. 57 

put too high a value on what is termed direct heating 
surface, in contradistinction to indirect or flue surface. 
A square foot of surface in a fire-box of ordinary con- 
struction has 2J to 4 times the vakie of the same area 
of average tube surface^ but they should not convey 
the idea that by increasing surface near or in the 
fire-box and decreasing the tube surface near or in 
the direction of the chimney in a threefold proportion 
to the increase in the fire-box, that they can evaporate 
as much water with the decreased surfaces. Makers 
of cast-iron boilers often make this claim. When a 
fire-box or furnace is large enough for proper com- 
bustion, its surface is then receiving all the radiant 
heat there is. By increasing the surface directly ex- 
posed to the action of the fire (beyond the required 
chamber for combustion), it will be necessary to have 
the surface of the fire-box as a whole more remote from 
the fire, and the radiant heat from any source has its 
effect decreased, directly as the surface ivhich absorbs 
it. Extended surfaces are little or no good on the fire 
side of the furnace. 

From a central point of heat the rays diverge on all 
sides, and the intensity diminishes invei'sely as the 
square of the distance, which will be found to be directly 
as the surfaces of different sized spheres, luhich might 
surround it. The value of the heating surface (for 
radiant heat) decreases for each unit of distance, in a 
geometrical progression ; in other words, twice the 
distance, one-quarter the heat. The above can be 
likened to the fire in an upright boiler. 

In horizontal boilers, or boilers with long fire-boxes, 
or ones fired within horizontal cylindrical furnaces, 
the fire can be likened to a long column of heat, from 



58 STEAM HEATING FOR BUILDINGS. 

which the rays go off parallel to each other in the line 
of its length, but diverge in a line of its cross section ; 
which will give a progression whose ratio is 2 as the 
decreased value of the surface for each distance it is 
removed from the fire ; in other words, twice the dis- 
tance, half the heat. But in any case, the assertion 
that the intensity of radiant heat decreases directly 
as the surface which absorbs it will hold good for 
any shape of fire or any shape of furnace, and hang- 
ing tubes, projections, or corrugations in a fire-box 
receive nothing from the radiant heat that would not 
be received by the plain surface ; so, although a 
person may take 4 foot of tube surface away, and add 
one foot to the fire-box without perceiving they lost 
anything, yet they cannot, in a boiler that is already \ 
furnace, and f flue, whose gases of combustion escape 
at a sufficiently low temperature, take away all the 
flues, or a large percentage of them, and by adding 
J of their surface to the fire-box, makes as much 
steam. 

All that can be gained by crowding the fire-box 
with surfaces, hanging or otherwise (which must not 
interfere with combustion), is, to reduce the bulk of 
the boiler ; the surfaces will be the same still, for the 
same work. It is therefore poor economy to reduce 
th6 size, when nothing else is gained, and make sur- 
faces which will fill up on the inside with sediment^ 
choke up in the tubes, or between them with soot and 
ash, and wear out in one-third of the ordinary time. 

It is an incontrovertible fact that boilers with very 
small parts require more surface for the same work 
done than with large and plain parts, because of the 
impossibility to thoroughly clean them and the 



HEATING SURFACES OF BOILERS. 59 

rapidity with wliicli tliey choke, the nearness of the 
tubes allowing the dirt to bridge between them. 

A maximum of fire-box with a minimum of flues is, 
however, proper, and should be the rule in house 
heating, where there is generally plenty of room in 
the cellar. 

If the surface of the fire-box be increased by 
projections or corrugations, for the purpose of an 
increase of surface in contact with the highly heated 
gases of the furnace, the folds should be large and in 
vertical row^s, so nothing can find a lodgment on them. 
The boilers which have given the best evapora- 
tive results, as well as the least trouble, and lasted the 
longest, have been the simplest, and the evaporative 
results of a boiler depend more on the care with which 
they are kept clean, and the unimpeded circulation of 
the w^ater within them, than on any peculiar disposition 
of the heating surface. 

Large boilers, compared to the work, are most eco- 
nomical, but the limit is hard to fix. There are so 
many conditions to be taken into consideration, as 
w^ell as styles of boilers, and as it is really the size of 
the grate and the velocity of the draft, compared to 
the work to be done (after the boiler is large enough 
to make sufficient steam), which regulate the economy 
hence a sufficiency or reasonable excess of boiler with 
the proper grate surface to burn the fuel required accom- 
plishes the most satisfactory results. 

A boiler that may do fairly well for the first year 
may not give satisfaction the second year. Such will 
be the case with boilers barely sufficient for the work, 
which, while they are clean and the person in charge 
of them has a pride in doing w^ell, will pass muster; 



60 STEAM HEATING FOR BUILDINGS. 

but during the second year, when the novelty has passed 
off, it may be quite different. Complaints may be 
heard, and one investigating a steam-heating apparatus 
with a view to putting it in his house may be apt to 
reject it should he inquire no farther. 

In proportioning the size of boilers for heating 
apparatus all calculations should be based on the sup- 
position that the boiler will be neglected to a certain 
extent, and that there are parts of the best boilers 
which cannot be properly cleaned, and that all boilers 
deteriorate in transmissive power (the gravity return 
least of all, as the return water is pure) more rapidly 
at first, until a point is reached where external 
deposits fall off, after which the impairment is slow, 
and caused only by slight deposits on the inside, 
chiefly oxides, which have a high transmissive power 
themselves. 

Can a boiler, it may be asked, be robbed of its 
heat by the gases of combustion, by retaining them 
too long in contact in passing through long flues ? 
Not if they are internal tubes or flues ; but there is a 
point beyond which there is no gain — namely, where 
the temperature of the gas and the steam becomes 
the same. Up to that point the gases of combustion, 
being the hotter, impart heat to the flue, but beyond 
it neither the flue can impart heat to the gas nor the 
gas to the flue, as they are of the same temperature. 
Boilers, when they are new, should have some such 
point, which simply moves nearer the chimney as 
they become old and dirty. 

The rate of combustion will also give this point a 
variable position, for the time being. 

Some engineers think it preferable to let the gases 



HEATING SURFACES OF BOILERS. 61 

of combustion escape at a liiglier temperature than 
the steam. In that case the point can be assumed to 
represent any constant difference of temperature of the 
gas above the steam. 

Reverberatory, or drop flues, in upright boilers, 
save much heat. A cause of loss of heat, in upright 
boilers (and possibly in many other boilers), which 
have a great many tubes, many more than the aggre- 
gate area of the chimney, is that the heated gases find 
the tubes directly over the fire and pass out rapidly 
at a high heat, of their own gravity, leaving the gas in 
the outer rings of tubes inert, as may be seen in 
almost any upright boiler, where the tubes of the 
outer circles are generally found clogged with dirt; 
the velocity of the draft in the middle tubes keeping 
them comparatively clean. But when there is a row 
of drop tubes, as shown in Fig. 37, or a flue built 
around the outside of the shell of the boiler with 
brickwork, with the chimney flue leading from the 
bottom, as shown in Fig. 36, the gases are then draivn 
out or " exhausted " by the heat in the chimney ; and 
the gases around the upper part of the boiler become 
uniform in temperature, and stratify, the lowest being 
drawn off first, and the others following according to 
their temperature. 

When combustion is good, and the gases as they 
leave the boiler and enter the chimney flue have not 
too high a temperature, the ivater within such a boiler 
has ahsorhed all the available heat; hence, to increase 
the surface of such a boiler, will not do much good* 
unless the grate surface is also increased ; since all 
the heat evolved has been absorbed. 

Note. — Figs. 36 and 37 are in Chapter VI, 



62 STEAM HEATING FOR BUILDINGS. 

Will the quantity of water within a boiler effect 
evaporation ? 

Many steam heaters and others use boilers com- 
posed of very small parts, so as to have the greatest 
surface with the least water, with a view to evaporate 
more water in a given time, and cite the time hetiveen 
starting the fire and the time steam is up as a proof of 
it. This is a mistake ! The reason why steam is got- 
ten up quicker, is because there is less water to heat 
to 212° before steam begins to make, but beyond that, 
the result, with regard to steam making is the same, 
for the same surface, other things being equal. 

What is gained in first time, with sensitive boilers, 
is more than compensated for, in house heating, by 
having boilers which contain a large quantity of water, 
that hold their steam when a new fire is put in. 
Boilers which contain small quantities of water are 
rapidly chilled, as well as rapidly heated, and must be 
fired often, and regularly. 

Fire engine boilers require to be sensitive, and 
when much power with small weight is a desideratum 
they are all right, but they are not lit for house warm- 
ing, nor are very sensitive boilers of any description. 



CHAPTER V. 

BOILERS FOR HOUSE HEATING. 

Boilers for heating apparatus should have very 
few parts, and be as simple as it is possible to make 
them, every part of them being constructed with a view 
to permanency, and parts that wear out more rapidly, 
such as grates, should be so arranged that they can be 
renewed by the most inexperienced person. 

Requirements for house heating boilers are : 
1st. They should contain a quantity of water above 
the safe line sufficiently large to fill the pipes and radi 
ators with steam, to any required pressure, loitliout 
lowering the luater enough in the boiler to require an addi- 
tion when steam is up. Should it be necessary to put 
additional water into a heating boiler, because the 
pressure has gone up and some water has disappeared 
from the glass, it will be found there will be too much 
water in the boiler when the steam falls again, making 
it necessary to take water from the boiler to prevent 
flooding. This is bad practice. It occurs in boilers 
made with very small parts or pipes, which have a 
small capacity. Should such a boiler have an automatic 
water feeder, set for the true water line, it will fill 
up, but it cannot discharge the water again when the 
steam goes down; while if it has no feeder, there is 
danger of spoiling the boiler for want of water, as too 
great a proportion of the water is in the pipes in the 
form of steam.^ 

* For the quantity of water necessary to fill the pipes with steam at 
any pressure, at a maximum density, see Table 13. 

63 



64 STEAM HEATING FOR BUILD IMG S. 

2d. The fire box is better made of iron, with a water 
space around it, as in upright or locomotive boilers, 
to prevent clinkering on the sides and the necessity of 
repairs to brickwork ; which are unavoidable in brick 
furnaces. 

od. The fire box should be deep, below the fire 
door ; to admit of a thick fire, to last all night, and 
thus keep up steam for a long period. 

4th. The fire-box should be spacious, for the sake 
of good combustion. 

5th. The flues and tubes should be large, and in a 
vertical position, so they will not foul easily, and that 
any deposit may fall to the bottom or into the fire. 

6th. The heating surface should be great in its 
diameter instead of in the direction of the chimney. 

7th. They should, if possible, be constructed of such 
shape and design that they will require no sweeping, 
or cleaning, other than removing the ashes, but when 
it is unavoidable, every facility should be made for 
easy access to such parts, as they are often operated by 
inexperienced persons (house servants), who naturally 
iind fault with anything that gives them trouble. 

8th. The fire-grate must be easy to clean and so 
designed that it will not crack or break when heated. 
Grates of the shaking or rocking pattern only should 
be used, and they should not be too fine. (See article on 
grates). 

9tli. The grate and ash-door must be so constructed 
that a new grate can be put in quickly by any one. 

loth. There should be no tight dampers in the 
chimney flue, and when the flue goes out near the 
bottom (drop flue), they may be dispensed with alto- 
gether ; but the fire and draft-doors should be made 



BOILERS FOR HOUSE HEATING. 65 

to close air-tiglit, so as to be capable of entirely damp- 
ing the fire. This will prevent the possibility of coal 
gas escaping into the house. The damping of a fire 
by shutting off its supply of air, is the proper way for 
blouse work, as the draft of the chimney being unim- 
p;iired, it draws all the harder on any crack or crevice 
in the brickwork, causing an inward current, which 
entirely precludes the escape of gas into the house. 

11th. The perpendicular height of the boiler should 
not be too great for the cellar, or the water line will be 
too near the main pipes or radiators. 

12th. A boiler should be so enclosed in brickwork 
or asbestos or magnesia coverings as not to perceptibly 
raise the temj)erature of the cellar in which it is. 
This also makes the whole outside of the boiler heat- 
ing surface if required, by having either an upward or 
downward flue.^ 

When upright boilers are constructed with drop 
tubes, as shown at a\ Fig. 37, or with drop flues, as 
shown in Fig. 36, it is generally necessary to use a 
direct smoke pipe as well as a bottom pipe, as shown, 
in which case an upper damper is required and possi- 
bly it is better to have a lower damper also. The two 
dampers should be connected at right angles to each 
other by a rod, as shown at i, Fig. 37, which pre- 
vents the possibility of having both dampers closed 
together. 

In upright boilers for house heating, the pro- 
portion of fire-box to the flue surface admits of almost 
any modification, as the boiler can be made of large 
diameter, with short tubes and high fire-box drawn in 

■^ Asbestos lined jackets of iron, or other suitable jackets of refractory 
materials, may take the place of the brickwork. 



66 STEAM HEATING FOR BUILDINGS. 

at the bottom with dead plates, for the desired size of 
grate, or drawn in as shown in Fig. 35. 

Horizontal multi-tubular boilers admit of very 
little modification ; a large diameter, with short shell 
and large tubes being best for slow combustion, Avith 
a considerable distance between the grate and boiler, 
and no bridge-wall higher than is sufficient to keep 
the fire on the grate. 

A chamber behind the bridge-wall is not of any 
particular service, when the bridge wall is low; and 
making a contracted throat, at the bridge-wall, or 
behind it, to make the heat '' hug " the boiler, is a 
mistake. What is wanted in the furnace, and under 
the whole length of the boilerg is space sufficient for 
complete combustion. Below a certain size of cross 
section combustion is interfered with, and the oxygen 
which passes through the fire will not combine with 
the carbon, but with ample space ignition will be con- 
tinuous until combustion is complete with a sufficiency 
of oxygen, where the temperature is not below (800°) 
eight hundred degrees Fahr. 

For a high rate of combustion the boiler may be 
longer, with tubes of small diameter and with great 
space under the boiler. 

A contracted passage, or one having only the 
area of the chimney at the bridge-wall, may cause 
more heat to impinge on that particular part of the 
boiler, but it will not cause the evolution of more 
heat. The sum total of the heat remaining the same, 
it will do the same duty, whether absorbed by a small 
part of the boiler, to which it may do injury, or by 
the whole surface at a more general temperature. 

The extent of the sides of the furnace, when made 



BOILERS FOR HOUSE HEATING. 



67 




of brick, may be used as an argument against a large 
fire chamber; but the loss through a well-made brick 
wall by infiltration of air or by radiation is so little that 
it will not offset the benefit due to complete combustion. 
Figs. 47, 48, and 49 show a horizoutal multi-tubular 
boiler, as ordinarily set ; 47 being longitudinal sec- 
tion, 48 half front and half cross section, and 49 floor 
plan.* 

The different parts of boilers and their settings 
have technical r=' 
names, applying ' 
to the corres- 
ponding parts of 
all boilers, as 
far as the con- 
struction will 
permit; the 
shape, some- 
times, modifyiug 
the name, and 
increasiug or les- 
sening the j)arts. 
As an example, a 
return^flue boiler, 

and a drop-return-Jlue boiler are shown. (Figs. 32 and 
33). 

The return-flue boiler can be used as a stationary 
or marine boiler with or without a water-bottom ; the 
drop-return being generally constructed for stationary 
boilers, as it has no steam chimney, and the smoke 
connection is a sheet-iron breeching. 

* The proportions for boiler and setting, shown in Plate 2, are better 
ihan those just mentioned. 







Fig. 32. 



68 



STEAM HEATING FOR BUILDINGS. 



The following are the names or principal divisions 
of a boiler, and similar letters apply to similar parts 
in Figs. 32, 33, 47, 48 and 49 ; 

A. Boiler-shell. 

B. Steam-dome. 

C. Boiler heads. 

C. Flue sheets. 

D. Tube. 

F. Flues. 

G. Back connection. 

H. Front " or smoke connection. 

I Smoke 

e/. Furnace, or fire-box. 




Fig. 33. 

K. Ash-pit. 

L. AVater-bottom. 

M. Steam chimney (marine). 

N. Smoke chimney (marine). 

0. Man-hole, to back connection. 

P. Bridge-wall. (See Fig. 47.) 

Q. Braces. 

R. Stay, or socket bolts. 

S. Grate bars. 

T. Coking, or dead-plates. 



BOILERS FOR HOUSE HEATING. 69 

U. Front-bearer. (See Fig. 47.) 

F. Back-bearer. (See Fig. 47.) 

W. Divisiou, between front connection and fire-box. 

(Fig. 47). 
X Boiier-fronts, cast-iron. 
r. Side walls. 
Z, Lugs. 

The division between furnaces, and the sides of fur- 
naces, are called "Legs "in fire-box boilers. 

The same letters apply to the corresponding i/s-aCS 
of the horizontal boilers, Figs. 47, 48, 49. 



CHAPTER VI. 

FORMS OF BOILERS USED IN HEATING. 

The conditions required for heating boilers, which 
nre of such proportions that they may be fitted up to 
work automatically, are simplicity of construction, 
durability of parts, and ordinary economy in firing. 

A source of danger to the success of the young 
steam-fitter and to others inexperienced in steam-fit- 
ting, is their endeavor to construct ideal boilers, 
which usuall}^ prove to be failures. It is far better to 
use boilers proved successful by others, and improve 
their weak points from experience with them. Suc- 
cess lies in that which will give least trouble, and will 
not wear out rapidly — the burning of a few tons of 
coal more or less in a year is not a proper test ; as 
the conditions of management, the size of the house, 
the amount of ventilation, the number of hours the 
apparatus is operated in the year, and last, though not 
least, the comfort and satisfaction — all must be taken 
into consideration to prove economy. 

rig. 34 shows probably the simplest form of 
upright boiler used for heating, excepting, perhaps, 
one with a flat crown sheet. The grate is drawn in at 
the bottom, by a slanting annular dead plate, as 

70 



FORMS OF BOILERS USED IN HEATING, 



71 



shown ; the center part of the grate only has openhigs. 
The brick-work is very simple, and is built around the 
boiler, leaving about a three-inch space for a flue, and 
the smoke pipe is taken out at the bottom. It does 
not rate very high in point of economy of fuel ; but it 
is very easily kept clean, and lasts a long time. They 
are now seldom seen. 

Fig 35 shows an upright boiler (multi-tubular), 
which is drawn in at the fire-box, to the size for the 

grate. This dis- 
^^^^ penses with the an- 

nular dead plate, 
and makes a very 
permanent piece of 
work. This boiler 
is set to carry the 
heat, when it leaves 
the tubes down one 
side of the boiler, 
and up the other, 
passing under a sep- 
tum of iron, or a 
division wall, which 
may be run very 
near the boiler, but 
so as not to press against it. When the tubes of this 
boiler are not smaller than two and a half inches, or 
longer than three feet, and nothing but hard coal is 
used, it will require cleaning but once a year, provided 
there is no leak in the fire-box, or about the ends of 
the tubes.* To clean the boiler, — remove the cover 

* Much moisture causes the fine white ash, which comes from hard 
coal, to bake on the heating surfaces, and should be prevented. 




Fig. 34. 



72 



BTEAM HEATING FOR BUILDINGS. 



a', and use a steel wire tube brush. The cover a' is 
covered with abestos or magnesia on the top, and in 
the space c, around the top, to prevent radiation, or 
danger from fire. It will be noticed, this boiler is 
set on a cast-iron plate, to give it stability. This 
plate is more satisfactorily made in two parts, and 
bolted together, which will prevent the heat of the 




Fig 35. 

fire from cracKng it, after it is set. The grate is 
here shown, a little higher than it is usually set ; but 
it would be well to keep it as high as the rivets. 

Fig 36 shows the ordinary upright boiler, set for 
heating. It has a peculiar steam dome, as shown, 
which prevents an excessive heat on top, and it is 
claimed slightly superheats the steam. It also 



FORMS OF BOILERS USED IN HEATING. 



73 



has an asli-sifting grate below the regular grate 
which saves much dust iu the manipulating of ashes, 
and prevents the grate proper from burning out 
rapidly. 

The form of dome shown here prevents the cleaning 
of the boiler tubes except with a steam blower. The 




Fig. 36. 



connections between boiler and dome have also to be 
of very large diameter, and circulating pipes — not 
shown — are necessary to take the condensation or water 
carried into the dome back to the boiler. Y/hen they 
are omitted the water carried into the dome is carried 



74 



STEAM HEATING FOR BUILDIN08. 



over into the heating jDipes, and much noise in the 
apparatus is the result. 




Fig. 37. 




Fig. 3S. 

Figs. 37 and 38 show an upright multi-tiibular re- 
verheratory tube boiler. Fig. 37 is a vertical section on 



FORMS OF B0ILER8 USED IN HEATING. 75 

a center line, and Fig. 38 a lialf cross-section, to show 
the walls and tubes. In Fig. 37, F P is the fire-pot, or 
dead plate ; F, the fire-box or furnace ; Gj the grate ; 
Hj a bar set in the brickwork of the ash-pit in such a 
way it may be removed to put in a new grate, and into 
which the grate is pivoted, a certain distance below 
the edge of the fire-pot, to admit of shaking and clean- 
ing from the bottom. The amount of opening is 
regulated by washers on the pivot of the grate, to suit 
the size of coal used ; 0, the direct tubes ; a', the re- 
verberatory tubes ; J, the bottom plate ; IT, the cover ; 
L, the direct chimney flue ; 31, the bottom or drop 
chimne}- flue. 

In point of economy of fuel, probably there is no 
house-heating boiler stands higher than this, if prop- 
erly proportioned, and in permanency it is fully equal 
to any wrought- iron boiler used; besides, it is not 
difiicult to clean. It will be seen that all the flues are 
internal, and if the gases of combustion cannot impart 
any heat to the boiler, after cooling to a certain 
degree, they cannot abstract any from it, as happens 
in external flues, when the gases cool to the tempera- 
ture of the steam or below it, by an admixture of air 
through the brickwork before reaching the chimney. 

It is also an excellent boiler where light power is 
desired, in which case the tubes may be of smaller 
diameter than would be used for heating, and longer, 
to suit a higher rate of combustion. 

When upright boilers are enclosed in brickwork, 
the outside is usually built square, to suit the door 
castings, and for appearance ; but the inside is gen- 
erally built round, three or four inches from the 
boiler, to make a flue or an air space, which will be 



76 



STEAM HEATING FOR BUILDINGS. 



the same distance from the boiler at every part. A 
wall so built generally cracks in the thinnest part, 
which makes it necessary to bnild the wall square 
inside and outside, as shown with cleaning doors at 




Fig. 39- 

corners. The infilteration of air through the walls of 
brick-set boilers is a great source of loss. 

When wrought-iron boilers are constructed for low- 
pressure heating, have them built just the ^ame as 



FORMS OF BOILERS USED IN HEATING. 77 

if they were intended to carry high steam, taking care 
the leg, the part formed by the side of the fire-box, 
and the shell, is properly stayed with socket-bolts, or 
stay-bolts, as boiler-makers often show a disposition 
to leave the legs unstayed, when they know the boiler 
is for very low pressure. 

Fig. 39 represents this boiler when set and fully 
fitted with the necessary self-acting appurtenances. 
A is the main steam pipe, which must be run for no 
other purpose but to distribute steam to the heaters • 
B, the safety valve, with its auxiliary diaphragm ; C, 
the draft-door regulator (the pipe carried up inside 
the brickwork) ; i>, the fire-door regulator, which is 
not absolutely necessary ; but it is well to have, in 
case anything should prevent the draft-door from 
closing ; E, the automatic water regulator, whose con. 
nections should not be a branch, from any other pipe 
— nor should they be branched for any purpose ; F, 
the main return pipe, which should have no valves in 
it, unless there are valves in the main steam pipe to 
correspond. When there is but one boiler, it is gen- 
erally better to dispense with valves in steam and 
return pipes at the boiler. G, the gauge cock, which 
for cleanliness may have a drip-pan under it, con- 
nected with the ash-pan ; H, the blow-off cock, which 
in a heating apparatus should never he connected directly 
loith the sewer or drain, but should be a lever handle 
cock over a funnel, as shown, to prevent the possibility 
of water passing out of the boiler without the knowl- 
edge of the person in charge. The funnel can be re- 
moved when not in use. /, the fire-door, on a good 
slant, so as to form a shute for the coal, and to close 
without a latch ; e/, the draft-door, an attachment to 



78 



STEAM HEATING FOB BUILDINGS. 



the ash-door ; K, the ash-door, which is hinged to the 
frame L, and will open without interfering with the 
draft-door ; the chain and the bolt having nearly the 
same common axis / L, the ash-door frame, which is 
bolted to a skeleton frame, built into the brick work> 
that can be removed to put in a new grate ; 3131, are 
hand holes, to clean the space at the bottom of the 
drop tubes ; Ny a hand hole, to clean the upper tube 

Ia 




Fig. 40. 

sheet, and through which a steam tube cleaner may 
be used, if desired. 

Fig. 40 represents a wrought-iron boiler, which 
came into public notice about 1876, and has given good 
satisfaction.* 

* It was patented by Mr. Wm. B. Dunning, of Geneva, N. Y. 



FORMS IN BOILERS USED IN HEATING. 79 

It is a reverberator J tvhe boiler, with a coal maga- 
zine, similar to the base burning stoves, and is entirely 
constructed of wrought iron, except the cast-iron mag- 
azine. When set, according to the manufacturer's 
instructions, every part of the boiler is exposed as 
heating surface ; the heat passes between the maga- 
zine and the fire-box, and thence down the drop 
tubes, D, and up and around the shell. The magazine 
is made to pull out, and care should be taken when 
setting them, to have sufficient room overhead to 
accomplish this. 

The heating boilers I have so far shown are all of 
wrought iron types. Since first writing this book, 
however, many cast iron house heating boilers have 
appeared in the market. 

Presumably the first cast iron sectional boiler to 
make any appreciable headway and to remain perma- 
nently in the market is the "Mills" Boiler, made by 
The H. B. Smith Co., of New York. It consists of a 
number of cast iron sections A A, such as shown in 
Fig. 41, joined to a steam drum B, and to two water 
headers B' and B' by locknut nipples. The sections 
A A are practically upright tubular units, two of 
which when put together in the manner shown, form 
what is called a section, their depth being about six 
inches. A number of these sections are added 
together to form the boiler. The sides of the ash pit 
P may be formed of masonry so as to form flues F F 
with the outside brickwork C. The sections are then 
built together on plates covering these flues, which 
form a foundation. The grate line is at G. The 
direction of the fire, therefore, is backwards and 
upwards from the grate, returning to the front 



80 




Fitf. 4i4. 




31 



82 STEAM HEATING FOR BUILDINGS. 

through the flues E and again returning to the rear of 
the boiler through the flues F. The boiler is usually 
enclosed in brickwork as shown. It is a type of 
boiler that can be used for power when the pressures 
are not very high, as well as for heating. 

The boiler shown in Fig. 42, made by the same 
company, is a later type of this boiler which does not 
require a brick setting. It is somewhat low in heating 
surface as compared with its grate surface — a fault 
in many of the earher types of cast-iron sectional 
boilers whose sections fit closely together. This will 
be noticed in comparison with the '^Mills'' and the 
'^Gurney" boilers, which have a high rating of heating 
surface as compared with their grate surfaces. As will 
be seen, there is a special front section with fire-box sec- 
tions and a rear section all connected with the steam 
drum on top and with the return water drums on each 
side of the bottom. The course of the flame and flue 
gases are shown by the arrows. It is furnished with 
shaking grates that cut up the clinkers. When the 
boiler is put together, it receives a coat of plastic 
asbestos cement which clinches between the tee bars 
T, making a permanent and smooth finish. The illus- 
tration is so good that other details of construction 
can be understood without further explanation. An 
earlier type of boiler somewhat like this, but which is 
not shown, was the " Gold " cast iron boiler. 

Another type of sectional boiler that is connected 
with headers in the manner just described is the Gur- 
ney, shown in Fig. 43 and 43a. It differs very mate- 
riafly from ah other cast-iron boilers by having its prin- 
cipal heating surface composed of horizontal circulating 
loops. A loop very similar to the Bundy radiator loop 
is screwed into the intermediate sections, as shown in the 



FORMS OF BOILERS USED IN HEATING. 



83 



centre of Fig. 43a, giving a very large quantity of heat- 
ing surface in a comparatively small space. A modi- 
fication of the same boiler is made circular in two sec- 
tions. They are made by the Gurney Heater Mfg. Co., 
of Boston. 

As an illustration of what may be done in a single 
casting, or almost a single casting, we show the boilers, 
Figs. 44 and 45. Fig. 44 is a boiler made in two parts, 
known as the Cottage. Fig. 44 shows the several sec- 
tions and also the arrangement of the parts, including the 




Fig. 44- Fig. 44a. 

grates, fire surface and flue passages. The upper pan 
forms the boiler proper made in a single casting. The 
flue gases pass backwards and upwards and forward 
through the two side flues, and return to the rear 
again through the centre flue. The mid-section shown 
in the illustration, forms a water leg about the fire, and 
the boiler proper and the water leg are joined together 



84 



STEAM HEATING FOR BUILDINGS. 



bj slip nipples. Pig. 44a shows the general appear- 
ance of the boiler when set up and used for steam. 

Fig. 45 shows a vertical water tube boiler made by 
the Gurney Heater Mfg. Co., of Boston, which may be 




Fig. 45.— (The Doric.) 

said to be made entirely of a single casting, and is so 
made so far as the water and steam parts of the boiler 
are coLicerned. The illustration shows the arrange- 
ment cf tiip l)nilpi- f ^ ili^Tf^ughly that comment is un- 



FORMS OF BOILERS USED IN HEATING. 



85 



necessary. The Cottage and the Doric boilers, of 
course, are made for comparatively small heating ap- 
paratus, while the other types of cast iron boilers run 
up to very large sizes and can be used in batteries for 
tl\e very largest description of work. 

Fig 46 shows a type of cast-iron sectional boiler 
put on the market by the A. A. Griffifig Iron Co., 
of New York. Its general difference from other boilers 




Fig. 46. 



of its class Hes in the fact that it is put together en- 
tirely by shp nipples, the ash pit being formed by the 
lower part of the section proper; the sections them- 
selves simply setting in an iron cradle on the founda- 
tion. The crown sheet of the fire-box is corrugated. 
The gases of combustion pass forward and backward 
through the tubes, the upper row being superheaters. 
These boilers, I am informed, are being used 



86 



STEAM HEATING FOR BUILDINGS, 



for both heating and power. They are called the 
^^Bundy." 

Fig. 47 shows the '^Richmond" cast-iron boiler. 
The heating surface is considerably increased in com- 




FiG. 47. 

parison with Fig. 42 by the addition of two rows of 
water tubes directly in the fire-box. 

Fig. 48 shows the ^^ Royal" cast-iron boiler. It 
is a good example of foundr}^ work and shows the 
sections running down and forming the sides of the ash 
pit. 



FORMS OF BOILERS USED IN HEATING. 



87 



Fig. 49 shows the ''Boynton" cast-iron boiler. The 
effort is to present a large heating surface to the direct 




Fig. 48. 

action of the fire. They are made in large sizes, and 
like the two boilers just previously shown, they are 
known as header boilers. 



88 



STEAM HEATING FOR BUILDINGS. 



Fig. 50 shows the ''Ideal" cast-iron boiler, which is 
made by the American Radiator Co. It will be noted 
that it is a sHp nipple boiler. The large sizes (one of 



9 



■?—--- 



:;--'■■ ;-:^?P»?s^s*^^*^^;^f-*^7^; "■"""" 




Fig. 49. 



which is shown) are peculiarly put together at the top 
in half sections— right and left. The object is to make 
portable pieces and to give greater strength. The flue 
passages are plainly shown. 



FORMS OF BOILERS USED L\ HEATING. 89 

From the cast-iron and house series of boilers which 
are generally used for low or moderate pressures of 




Fig. 



so- 



steam and for warming purposes only, we pass to the 
high-pressure or power boilers. The power-boilers are 
shown in plates at the back of the book. 



90 STEAM HEATING FOR BUILDINGS. 



THE HORIZONTAL MULTI-TUBULAR BOILER. 

Plate 3 shows a longitudinal section, a half-front 
elevation and half-cross section, a section at back, and 
a plan of an ordinary horizontal boiler, set for heating 
or for power. 

This is a style of boiler much in use in the United 
States, when the building is of such proportions that 
it requires pressures greater than can be used in cast- 
iron boilers, and considerable notice will be given to 
it, its method of construction, setting and so forth, 
as it is the typical American boiler. They are some- 
times fitted with automatic appurtenances, but where 
two or more of them are in a building, automatic 
draft regulators are all that should be used, and a 
careful engineer or fireman should do the rest. 

When used for power where the water contains mud, 
as in some western cities, they should be fitted with 
a mud pipe, as shown in Fig. 51, or if used for heat- 
ing when the water is wasted; but this is scarcely 
necessary in a gravity apparatus. 

Fig. 51 shows a horizontal boiler where the front 
end of the shell is supported by resting in the cast- 
iron front; with the front connection formed by what 
is known as breeching; this is sometimes made of Jight 
iron and bolted on; but it is better to form it by an 
extension of the boiler shell, as shown. 

There seems to be a dishke to this front, for no bet- 
ter reason than because it is not considered ornamen- 
tal. It is certainly a substantial front, if made in 
sections and bolted about the doors, where all fronts 



FORMS OF BOILERS USED IN HEATING. 



91 



are liable to crack, and if set as shown with deep dead- 
plate and two courses of firebrick lining, it will seldom 
require repairs ; but if the front bearer is bolted to 
the cast front, and the front is lined with a single 
course of fire-bricks, held in their place around the 
door by a cast-iron frame, the frame will burn off, the 




Fig. 51. 



lining fall down, and the front become heated and 
cracked. With a straight or "flush" front, a dead 
plate is always used, to keep the fire away from the 
front connection. The thickness of the wall necessary 
to form the front connection forms a fining for the 
front, which must be kept in repair. If the dead plate 
is used and made sufficiently deep, the front will last 
pretty well. 

This front and setting also obviates the necessity 
for the projection shown in Fig. 51. 



92 STEAM HEATING FOR BUILDINGS.. 

Plate 2 shows a horizontal multi-tubular boiler, 
similar to the boiler shown 'n Plate III, but with the 
improved cast-iron fire-door arch A ; with the man- 
hole on the shell, domed steam drum, flat gusset 
braces, and other details of a modern steel boiler. 

It was usual to make the shells of No. 1 charcos'- 
liauimered iron — though nearly all are now made ot 
;i line grade of boiler steel. When steel is used, 
shells up to 42 inches should be made of ^-inch plate ; 
from 42'' to 48'' of ^ thick plate, and from 48" to 60" 
of f to ^ thick plate ; with head sheets of f to -^-^ and 
\ respectively, shells and heads being constructed of 
best flange steel. 

The domes of these boilers are usually made 
one-half the diameter of the shells, and about 
the same height; but the limited height of cellars 
often reduces the height of the dome, and in some 
cases renders it necessary to dispense with them 
altogether. 

The height for the setting of a 48-inch shell should 
not be less than 11 feet, and as much more as can be 
conveniently had. This will allow 2 feet from the 
paving of the ash-pit to the grate, and 2 fe^t more from 
the grate to the boiler, 4 feet for the boiler and 2 feet 
for the dome, leaving 1 foot from top of dome to 
underside of sidewalk or floor beams. For each addi- 
tional foot of diameter of boiler 16 inches should be 
allowed. 

Low cellars are a detriment to a heating apparatus 
in another and very important respect — they bring 
the main steam pipe too near the water line of the 
boiler, ai?d make the use of mechanical devices neces- 
sary in work which otherwise could be made more 



FORMS OF BOILERS USED IN HEATING. 93 

perfect as a gravity apparatus. 

When tlie man-hole of a boiler is in the 1;op of the 
dome, a hole in the shell underneath the dome, large 
enough to easily admit a man from the dome into the 
shell is required. This is bad practice, as this large 
hole weakens the boiler materially; which fact 
engineers generally pay no attention to. The shell of 
a boiler underneath the dome should not be cut out 
unless it is reinforced in some proper manner ; but 
should be perforated with a number of small holes — 
say 2 inches in diameter — until their aggregate area is 
four or six times that of the steam pipes. 

When the man-hole is in the top of the boiler an 
extra heavy man-hole frame should be riveted to the 
shell ; its longest diameter being across the shell. 

The tubes in horizontal boilers give the best results 
when not " staggered," but placed in vertical rows 
and should have at least one inch between the tubes 
at their nearest parts, and should be not nearer the 
shell than 3 inches. 

These boilers should be tested to 150 or 200 lbs. per 
square inch by hydraulic pressure. This is abso- 
lutely necessary to test the bracing and other parts, 
such as heads and man-hole frames. 

There is a prevalent idea that testing a boiler with 
cold water may injure it. If a boiler will not stand 
twice the ordinary pressure it is made to carry with- 
out injury under a hydrostatic test, with water at 40 
degrees Fahrenheit, it should not he put into a huildingj 
and the constructor or engineer who makes such an 
assertion does so either through ignorance or through 
the fear that his apparatus is not up to a reasonable 
standard of strength. 



94 STEAM HEATING FOR BUILDINGS 

OTHER FIRE-TUBE BOILERS. 

Plate VII shows a fire-tube and shell boiler which is 
known as the ''Fitzgibbons." It is a modification of 
a locomotive and marine type of boiler, and it is now 
much used for heating and power work in buildings. 
It is built both as a heating and as a power boiler — • 
the difference being in thickness of material and in 
strength. The saving in room required for setting as 
compared with the locomotive type is quite apparent. 

Plate VIII shows the ''Scotch Marine" type of boiler. 
It can be built of great strength, but it is not a desirable 
type for buildings on account of the comparatively 
small allowance of heating surface per horse-power 
and the difficulty of getting it in or out of buildings. 
It is shown to acquaint the student with the type and 
its construction. 

Plate IX shows the ''Bigelow-Manning" type of boiler. 
It is a very high-class boiler of the upright fire-tube 
shell type, capable of standing very high pressures. 
It is very economical of floor space and is often used in 
high city buildings and hotels where room is very 
valuable. 

There are many other types of American fire-tube 
boilers. Space, however, will not permit us to show 
them all, and it is not necessary, as the principles are 
illustrated by those to which we have already referred. 

WATER-TUBE BOILERS. 

plate X shows the ''Babcock and Wilcox" water- 
tube boiler. It is probably the best known and most 



FORMS OF BOILERS USED IN HEATING. 95 

widely used form of water-tube boiler. The tubes are 
expanded into vertical or nearly vertical headers; both 
front and back and each header is connected to the 
steam and water drum through a circulating pipe. It 
will be noticed that the tubes are placed on an inchne 
and that the water passes through the tubes from back 
to front. The mud drum is placed below the headers 
at the rear of the boiler, with a connection from each 
header to the mud drum. 

For very high pressures these headers are made of 
steel and the yokes, nozzles, etc., attached to the drums 
are made of forged steel, so that no cast-iron parts are 
used. 

Plate XI shows a ^^Root" water-tube boiler. It is 
a very early type of the water-tube boiler. Its present 
form is made up of a number of two-pipe elements, the 
sections being arranged in vertical staggered rows 
and connected back and front with special bends and 
a pecuHar form of joint. Each vertical row connects 
into a steam and water drum, so that five, more or less, 
of these rows or larger elements make up a boiler, the 
drum of each large element connecting with the steam 
drums. Circulating pipes connect between the small 
drums and the back headers of the boiler, so as to 
give the water a circulation through the smaller 
drums. 

The large cross or steam drum is also connected to 
the rear cross headers by a dry pipe, so that any water 
carried over by the force of ebuUition or otherwise is 
returned to the lower part of the boiler from the upper 
or steam drum. 



96 STEAM HEATING FOR BUILDINGS. 

The method of setting and the other general form 
of parts is plainly shown in the illustration. 

Plate XII shows a '' Worthington" water-tube boiler. 
This boiler does' not require very much in the way of 
a brick setting as the headers practically form the ends 
or sides of the boiler setting. A hght iron casing 
(preferably covered with an asbestos or other insulating 
material) is placed outside the headers and arranged 
so that one can readily get at the caps at the ends of 
the tubes. It will be noticed that two large circulating 
pipes at both the front and the rear of the boiler run 
from the steam and water drum to a mud drum on 
either end or side. 

Each of the lower rows of nearly vertical headers 
connects to a mud drum and each of the upper rows 
of nearly vertical headers is connected to the steam 
and water drum. The boiler tubes run from the lower 
headers at one end or side of the boiler to the upper 
headers on the opposite end or side. 

The Worthington boiler provides a large amount of 
heating surface in a very compact space^ and the head 
room required by the boiler may also be made relatively 
small. 

Plate XIII shows the "Stirling" water-tube boiler. 
This boiler is a brick-set boiler with three large cross 
drums at the top and with one large cross drum at the 
bottom. A number of straight tubes bent at the ends 
connect each of the upper drums with the drum at the 
bottom. The upper drums are also connected together 
with a few short bent tubes, the two forward drums 
being connected with tubes to allow the passage of both 



FORMS OF BOILERS USED IN HEATING. 97 

steam and water, while the two rear drums are con- 
nected together above the water-Hne only. 

The water is fed into the upper rear drum and it 
will be noticed that a pan is provided in this drum into 
which dirt, etc., is supposed to be deposited. 

The water passes from the rear upper drum to the 
lower drum and these tubes (containing the coldest 
water) are surrounded by the coldest gases, or in other 
words, by the flue gases, which immediately afterwards 
pass to the chimney. 

The bent tubes are of advantage in so far as expansion 
is concerned, and although apparently they cannot be 
so readily cleaned as the straight tubes, nevertheless 
the manufacturers claim that (with the special clean- 
ing apparatus which they provide) the cleaning of these 
boilers is not an objection. 

Plate XIV shows a ''Heine" water-tube boiler. This 
boiler is a brick-set boiler with a long steam and water 
drum, furnished with a water leg at each end into which 
the straight tubes are expanded. A hand hole is located 
opposite the ends of each tube. One advantage that 
is claimed for this boiler is the large cross-sectional 
area of the water-leg between the tubes and the steam 
and water drum. On the other hand, an objection is 
sometimes raised to the rigid connections between the 
tubes and the steam drum, the idea being that the 
difference in expansion between the tubes and- the 
drum may cause a strain and consequent weakening 
where the water legs are attached to the drum. The 
fiat surfaces of the legs are fastened by stay bolts. 

Plate XV shows the ''Atlas" water-tube boiler. This 



98 STEAM HEATING FOR BUILDINGS. 

boiler is provided with water legs similar to those in the 
Heine boiler. Instead of one long drum at the top 
of the boiler, however, it has three cross drums, con- 
nected with tubes, some of which are above the water- 
hne of the boiler and are therefore to be regarded as 
superheating tubes. 

A strong point in favor of all water-tube boilers 
is their greater safety as compared with the shell 
boiler^ especially when a very high steam pressure is 
required. 

Ten square feet of heating surface in these boilers is 
usually rated as a boiler horse-power, while fifteen square 
feet is the usual boiler-makers' rating in the multi-tubular 
shell boiler. It may be stated, however, that ten square 
feet of heating surface in the multi-tubular boiler will 
be made to produce the steam required by one boiler 
horse-power and the multi-tubular shell boiler is now 
often rated on this basis in competition with water- 
tube boiler; if the fire-tubes are well proportioned to 
the work they have to do, this will be satisfactory, 
but it must be remembered, a short fire tube is waste- 
ful of fuel and a long one may absorb all the heat 
of the gases in two thirds its length; hence the 
variation in rating. 



CHAPTER YII. 

GENERAL REMARKS ON BOILER SETTING AND CON- 
STRUCTION. 

The best materials should be used in the set- 
tings of boilers, and less than a 12-inch wall should 
not be allowed even in the setting of the smallest class 
of Jiorizontal boilers. Large boilers should have not 
less than 12-inch walls in addition to the thickness 
of the fire-brick lining of the furnace, and 20, and 
24-inch walls are not uncommon. 

It is not desirable to put a number of masons on 
boiler walls and hurrj them ; for neatness and delib- 
eration are required with every brick, and makeshifts 
should never be allowed. 

On marshy, or sandy ground, it is well to exca- 
vate for the wdiole size of the apparatus and put in a 
thick concrete foundation, which will keep the work 
substantial and also help to cut off moisture from 
the earth. 

It is generally assumed that the greater expan- 
sion of the bricks on the inside of the furnace is the 
cause of the boiler walls cracking ; and it is, to a large 
extent true, though cracks from this cause are gener- 
ally distributed over the walls, and are not so great 
but that a few coats of whitewash are sufficient to 
fill them. 

99 



100 STEAM HEATING FOR BUILDINGS. 

The large fissures which often appear in sidewalls 
of boilers are usually caused by an insufficient found- 
ation, the walls resting on or against the boiler ; or 
by unequal or abrupt changes of thickness. Opposite 
the bridge-wall a crack usually appears which is sup- 
posed to be caused by the mass of the bridge-wall 
moving in a different direction to that of the wall. 
This crack nearly always appears, and as it opens 
under the heat, small particles sift down within it and 
prevent its closing when cold, and this action going on 
often opens a large fissure. 

The arch over the back-connection of a boiler 
should not be turned against the boiler-head, as is 
often the case, but should be sprung from the side 
walls ; with a rod to form the chord of the arch with 
the necessary flanges or buck staves on its ends, the 
rod to be just covered from the heat in the back 
wall. 

If it is desirable to turn the arch from the back 
wall to the back head of the boiler (since some think 
this shape more desirable), a heavy angle iron should 
be used to turn the arch against. The angle iron 
should be kept half an inch from the boiler, taking 
care no mortar or bits of brick lodge between the head 
of the boiler and the angle iron. 

When the lugs of a boiler are firmly built into the 
brickwork, without iron plates in the wall for the lugs 
to '* give and take " on, the walls will crack, because 
the iron of the boiler contracts and expands more 
than the wall does. The lugs should also be free 
from the brickwork on their ends and top. 

The arch, turned over a boiler, should not touch it, 
but there should be one or two inches of space 



BOILER SETTING AND CONSTRUCTION. 101 

between boiler and arch. The arch should spring 
from the side walls, and be self-supporting, and not 
turn on the boiler. 

A good way to build these arches is to lay inch 
strips of wood lengthwise on the boiler and draw 
them out as the work progresses. 

When boilers are not arched over, but the sidewalls 
are run straight up, and the space, over the boiler, 
filled with sand or loose materials, the walls are very 
apt to crack and be shoved out of plumb. Every 
time the boiler cools, the sand and loose particles will 
press down between the boiler and the wall, and the 
whole mass above will settle down. Then the boiler 
becomes heated again and expands ; the sand will not 
be forced up again ; hence the wall will be shoved out. 
This often happens, and it is attributed directly to 
the action of the heat, as something unavoidable, but 
such is usually not the case. 

When boilers are set on sandy ground the founda- 
tion should be deep and good, as the heat of the fur- 
nace will drive out the moisture from the sand and 
leave it a quicksand^ so that they should have a heavy 
foundation of concrete that the whole mass may settle 
as a monolith. 

An air space within a boiler wall is of doubtful 
utility, the same thickness of brick will prove more 
serviceable and will not weaken the wall."^ 

The fire-bricks in a furnace, should have the 
smallest possible quantity of fire-clay between them^ 
barely sufficient to level the work. They should be 

* I do not wish to convey the idea that a space in the walls of a build- 
ing is not valuable ; since it interrupts the passage of moisture, the evap- 
oration of which, from the walls, would require more heat than would be 
jost otherwise. 



102 STEAM HEATING FOR BUILDINGS. 

laid with a couple of courses of headers at the top, 
so the side linings could be removed without affecting 
the stability of the wall. The other courses should 
not have headers, but an occasional header to tie 
the face of the Avail, as the breaking out of a row of 
headers will injure the structure of the wall. 

The division ( Wy Fig. 47) between the furnace 
and the front-connection is another source of annoy- 
ance ; when constructed of iron it burns out rapidly, 
and when made of fire-brick, in the shape of an arch, 
it falls out ; or may be broken in using the fire-tools. 

Hollow castings, with air and water circulations in 
them, have been tried to form the under side of the 
front connection, but they do not last and are danger- 
ous under high steam pressure, as they are usually 
flat-sided. The shell of the boiler is sometimes 
allowed to project and cover this space ; but as it has 
heat on both sides of it, it buckles and burns out in 
a year or so, unless the engineer is very careful about 
keeping the brickwork in order. 

Sometimes the shell is extended with a water space, 
formed on it by a projection of the head sheet and 
shell, which forms a permanent fixture ; and if the 
part is well studded with stay-bolts there can be no 
objection to it ; but care must be taken, when a high 
pressure of steam is to be used, as this "shovel 
nose " (the name by which it is known) will form the 
weakest part of the boiler (see Fig 52). 

If an iron arch is used underneath a brick arch to 
support it and keep it from being knocked out, it will 
last longer ; but the inner edge of the casting will 
bulge and get out of shape long before the iron will 
6e burned away, which suggested to the writer, that 



BOILER SETTING AND CONSTRUCTION. 



103 



if the cast-iron arch (which should spring from the 
dead plate and form the doorway to the furnace) 
flared inward, and was cut into, for about one third 
its depth, making large and coarse prongs (about 2 
inches wide by six inches long, with one inch of a 
slot) to support and guard the bricks, it would stand 




Fig. 52. 

for a longer time. This method has been used many 
years, and the prongs do not bend down, while they 
burn off very slowly from their points, lasting three 
or four times as long as the ordinary cast-iron door 
frame. 

A deep dead-plate saves the front and door 
linings, as it keeps a body of comparatively dead 
coals between the front and the fire. 

Bridge walls are often built straight across, but 
an inverted arch is better ; though not on account of 
combustion, but that in an arch the bricks are keyed 
in, and are not as likely to be knocked out by the 
fire tools. 

Deep ash-pits are the best, and a second or ash- 
grate will help preserve the grate-proper ; as there is 
less reflection of heat from it than there would be 
from a hard brick bottom. 



104 STEAM HEATING FOR BtflLDINQS. 

The brackets riveted to sides of boilers to sup- 
port tliem in the brickwork are commonly called 
*Mugs," and many engineers, in the construction of 
what they consider long boilers, put three lugs on a 
side, fearing the weight will be too great for two 
only. This is undoubtedly a mistake, and frustrates 
the object for which the third is put on. The 
object of the extra lugs is to distribute and lessen the 
weight on any one lug. With a middle pair of lugs, 
however, the settling of the brickwork at one end will 
throw the whole weight of the boiler on the middle 
pair, and even if the walls should not settle, the heat- 
ing of the under side of the boiler more rapidly than 
the top, which takes place for instance upon starting 
a fire before steam is up, will in a great measure 
force up the ends of the boiler, leaving the whole 
weight on the middle pair of lugs. 

Four lugs, properly put on, are found to be the 
best number, and the detail. Figs. 53 and 54, page 106, 
shows a method introduced by the writer and now 
very much in use by careful boiler-makers. The 
lug is extended downwards, the part going against 
the side of the boiler covering a greater area of 
the boiler shell than usual, and bringing a row 
of rivets below the horizontal bracket of the lug. 
With the old-fashioned lug all the rivets are above 
the bracket, and the tendency of the weight is to put 
an undue strain on the rivets, which to many is sup- 
posed to be a shearing force, but which in reality is 
very much more of a pull in the direction of the 
length of the rivet, the tendency being to pull the 
rivet through the side of the boiler or break the rivet 
in its shank. When the lug is extended below the 



BOILER SETTING AND CONSTRUCTION. l05 

bracket, as shown in Fig. 53, the tendency to pull the 
rivet through the sheet is greatly lessened ; and, in 
fact, if the lug is properly proportioned, the strain on 
the rivet becomes almost entirely a shearing straiu, 
the resultant force being almost directly downwards, 
or the tendency of the bracket to tear off, almost 
directly upwards. 

It is a mistake also in setting boilers to neglect to 
get the support under the bracket close to the side 
cf the boiler, because when the bracket bears un- 
evenly, or near its outer end, on its roller, it increases 
the leverage to tear the bracket from the shell. 
Many initial ruptures in horizontal boilers occur 
underneath this bracket, and for this reason many 
makers of large and heavy boilers are abandoning the 
bracket and using the method shown in Plate VI, and 
one that has been used a great deal on river steamers 
in our western waters. Flat, wrought-iron or steel 
suspenders are riveted to the side of the boiler, which 
is supported on I-beams, crossing from wall to wall, 
as shown. With this style of support there is very 
little danger of tearing the suspender or " lug " from 
the side of the boiler, as the strain on the rivet is 
entirely a shearing strain, but there is danger of 
getting the pins or rods that run to the beams above 
too light ; and in designing the rods and suspeaders 
care must be taken that any two opposite suspenders 
will sustain the maximum load with safety, the maxi- 
mum load, of course, being the weight of the boiler 
when it is full of water. 

Lugs are sometimes left off until a boiler is in the 
basement, for the purpose of getting it through door- 
ways. This is not good practice, as the rivets should 



106 



STEAM HEATING FOR BUILDINGS. 



be driven on the line inside of tlie sliell, before the 
tubes are put in. Putting them on with tap bolts is 
not good practice eitlier, as two or three bolts may 
have to carry the whole end of the boiler. Bolts of 
%" or y diameter tapped into the side of a boiler, and 
loaded as a bracket bolt will be, are apt to break or 
strip in the thread, and there is no way by which the 
boiler maker can safely ascertain the load on a bolt. 
He is obliged to strain on the bolt until he draws the 
work close, at which time the bolt often breaks, or is 
ready to break, so that there is no factor for safety 
that can be depended upon. Should the bolts leak 
also under pressure, the brickwork has to be torn 
down to remedy the defect, and the work is often 
made tight with cotton wdck or some similar packing. 
A good plan when the lugs must be left off, is to 
have a shoe riveted to the boiler at the proper time, 
into which the lugs will slip, similarly to a stove leg, 
and which, of course, must be sufficiently strong for 
the work. 





Fig. 53* 



Fig. 54. 



Steel pressed lugs that take the place of the castings 
shown in Figs. 53 and 54 are now much used. 



CHAPTEK VIII. 

PROPORTIONS OF THE HEATING SURFACES OF BOILERS 
TO THE RADIATING SURFACES OF BUILDINGS. 

Theee is no simple relation between the heating 
surfaces of boilers and the radiating surfaces of the 
buildings they have to supply the steam to, as the 
following considerations modify every type of appa- 
ratus : The class of boiler used ; the method of 
setting boilers ; what the grate surface is ; the char- 
acter of the work the boilers are designed for, and 
whether the air is simply to be maintained at a certain 
temperature, as in direct radiation, or whether every 
cubic foot of air which comes in contact with the 
radiator must be warmed from the outside to tbe 
inside temperature, as in indirect radiation, or wdiethei- 
the apparatus is direct-indirect or composite. All these 
will have to be considered, and the results are then 
only close approximations to the truth. Neglect of 
cleaning, a certain amount of neglect of management 
and the state of the fire — whether on the first hour of 
the new fire, or the last hour of the dirty fire — for the 
time they are to run without attendance, all must 
enter into this calculation, and then one is generally 

107 



108 STEAM HEATING FOR BUILDINGS. 

forced to err on the side of safety — that is, not have 
just sufficient boiler to do the work, but a little more 
than enough to do the work under the poorest coudi- 
tions likely to be encountered. 

If the effect of the cooling produced by loss of 
heat through the glass and walls of a building can be 
properly estimated and added to the amouut of ht^at 
lost in warming the air admitted for ventilation, a 
close estimate can be made of the smallest gr.ite 
that will burn sufficient fuel to evaporate the required 
amount of water in a boiler sufficiently large, but not so 
large as to be wasteful. 

The amount of opening of the draft door or damper 
which regulates the fuel burned; the fuel burned regu- 
lates the water evaporated; and the water evaporated 
regulates the amount of steam made, so that really 
what is required are certain hmits within which an 
engineer knows he is safe, and to exceed which would 
be an unnecessary expense. 

Boilers for very large buildings which have an engi- 
neer in charge can be figured pretty closely, as he 
is supposed to be constantly at his post and to clean 
his boiler fires regularly, and to fire often and in 
small quantities; keeping his fire door open the short- 
est time possible, and further, to clean the tubes or 
flues whenever required. But this is not the case 
in house boilers. They must run long periods with- 
out cleaning or interruption, and be adequate to every 
contingency of change within their limit of time to 
keep steam without attendance. 

It has been found by experiment in a general \va\', 



PROPORTIOXS OF II E ATI X J SURFACES. 109 

and from practice, that for ordinary large buildings, 
with average window surface, and for the greatest 
range of temperature in our northern states, when 
nothing but direct radiation with no ventilation is 
used, one square foot of boiler to every ten square 
feet of the radiating surface will answer ; assuming, 
of course, the radiating surface is ample. This is an 
approximation for high pressure boilers only with 
fair to good draft, and though I have one case in New 
York where one square foot of average boiler surface 
supplies from 14 to 15 square feet of radiation, there 
are many boilers under the ordinary condition of 
setting with short or cramped chimneys that will 
not do better than 1 to 8, and this for low pressure 
steam only (2 to 10 pounds pressure), as, of course, 
the higher the steam pressure the greater the con. 
densation, a matter that will be referred to here- 
after. 

For indirect radiation, if the heating or radiating 
surface of the coils are double what they would be for 
direct radiation without ventilation, the same propor- 
tion of boiler to coil will about suffice ; but, if in- 
stead of doubhng, the building is kept warm by moving 
the air twice as fast with a fan, through a comparatively 
small coil, we must proportion the boiler the same 
as if we had double the heating surface, that is, 1 
of boiler to 5 of indirect radiator. These rules aic 
only the roughest of approximations and often lead 
to much blundering, and if one will only bear in mind 
that a boiler should be proportioned to the cooling 
which goes on — heating, ventilation, etc., — and not 
to the coil surface, as that is as variable as boilers 



no STEAM HEATING FOR BUILDINGS. 

themselves, they will not expect a direct answer to 
their question. 

For direct-indirect radiation, proportion the boiler 
about one and one half times what it would be for 
direct radiation. 

These estimates are for boilers with ordinary high 
combustion, such as horizontal boilers which are kept 
clean without interruption ; but for house boilers with 
slower combustion, an addition of J to J, depending 
on the type of boiler and good judgment, will be 
required on the part of the engineer. 

The manufacturers of the boiler shown in Fig. 34, 
made 3 sizes, of 45, 60, and 75 square feet of heat- 
ing surface, and rated them to furnish steam for 
300, 500, and 700 square feet of direct radiation coils. 
These boilers were used for many years in the early 
days of steam heating, and were probably not over- 
rated. They are of a simple type with direct surface, 
wherein the gases of consumption escaped into the 
chimney at a high temperature. They were not as 
economical of fuel as more modern boilers, but illus- 
trate a type in which the proportion is about one of 
boiler to 9 of radiating surface. 

The manufacturer of the upright tubular boiler, 
shown in Fig, 36, published a list of 24 sizes of boil- 
ers, from 54 square feet of surface to 400 square feet, 
in which he gives the maximum and miuimum num- 
l)er of cubic feet of air in ordinary buildiugs each 
boiler will carry radiation for. 



PROPORTIONS OF HEATING SURFACES, 111 

The following is a condensed table of this list : 



No. of Boiler. 


Feet of Surface 
of Boiler. 


Maximum and Minimum 

of Cubic Feet of Air iu 

Building. 


Square Feet of 
Radiation. 


1 

6 

9 

12 

18 

24 


54 
107 
151 
202 
302 
403 


18 to 25 thousand. 

40 " 54 

55 •' 75 

72 " 100 
116 " 152 
164 "215 


360 to 500 
800 "1080 
1100 " 1500 
1500 " 2000 
2320 " 3040 
3280 " 4300 



There is no doubt this list is approximately correct 
when upright multi-tubular boilers are used, or any 
kind of shell boilers, with simple parts. The propor- 
tion runs between 1 to 1^, and 1 to 10. 

In the Nason Manufacturing Company's old cata- 
logues on thin pipe boilers, a circular is to be found 
giving the following list — in which the grate to the 
heating surface of the boiler is about as one to 27, 
and the heating surface of the boiler to the radiating 
surface of the building 1 to 6|-. This was considered 
a safe and liberal allowance, which it proved to be, as 
under favorable conditions i to ^ more direct radiator 
surface would be carried by the boilers. 



Square feet of Grate 
Surface 

Square feet of Boiler 
Surface exposed to 
the fire 

Square feet of Radiat- 
ing Surface which it 
will heat 



3 


2i 


3 


3^ 


4 


4i 


5 


6 


55 


65 


78 


83 


105 


116 


131 


158 


350 


440 


525 


600 


700 


775 


900 


1050 



7 

182 

1225 



The proportion of grate surface shown here also 
gave good practical results. 
Morris, Tasker & Co., of Philadelphia, gave an early 



112 STEAM HEATING FOR BUILDINGS. 

list in which the rates are nearly the same, the variation 
for circumstances being greater. It is as follows: 



Feet of Surface of Boiler. 



115 
125 
133 

148 



Contents of the Building in Cubic Feet. 



18 to 30 thousand. 
26 "43 
37 "62 
55 " 92 



The foregoing remarks and the tables just given go 
to show the approximate relation between boilers 
and radiating surfaces. . In a subsequent chapter 
devoted to methods of calculation pertaining to steam 
heating data, founded more on the scientific principles 
of the matter, will be given, from which a better 
conception of the subject may be obtained by those 
who desire to go more thoroughly into the matier. 

One simple rule can always be borne in mind- 
namely, that 1 square foot of average boiler surface 
will evaporate 2 lbs. of water in an hour, and that be- 
tween 7 and 8 square feet of radiation will condense 
the same amount of water in the same time under 
average conditions. Of course boilers can be forced 
to 3 and 4 lbs. of water per square foot of heating sur- 
face, but this would not be good practice for house 
heating boilers. In power boilers such evaporation is 
common enough. 



CHAPTEK IX. 

GRATES AND CHIMNEYS. 

Foe a house heating apparatus the grate and 
fire-pot should be so constructed that as the fire 
burns the body of fuel will move together, centrally 
as well as downwards, and thus keep a compact body 
of ignited coal for a long time on the grate. When a 
grate is broad, with a thin fire on it, as in power 
boilers, the fire burns out at certain parts of the grate 
faster than at others, and a fireman has to build his 
fire accordingly, giving it constant attention to keep 
up steam and not waste coal ; but in a private house, 
all parts of the apparatus, including the grate and 
fire-box, must be constructed so that the fire can be 
left unattended for a comparatively long time ; and 
engineers unacquainted with this class of work will 
be surprised at what has been done in this respect, 8 
to 12 hours' duration being common for a fire to keep 
steam, and often make a better showing for the same 
weight of coal per radiating surface than large boilers 
with flat rectangular grates, fired regularly and ofteu, 
with a high rate of combustion. 

When a grate is surrounded with a fire-pot, or when 
the fire-box is drawn in to any angle not greater than 
about 30° from the perpendicular, the coal as it burns 

113 



114 STEAM HEATING FOR BUILDINGS. 

will press to the center and slip down, keeping the 
fire deep and in a good condition longer than when a 
furnace has perpendicular sides. The tapering fire- 
pot works well with a magazine-fed fire, as the 
tendency is to consolidate the fuel as it slips down- 
ward. Ordinarily, however, the sides of the fire-pot 
or fire-box are perpendicular, in which case it must be 
deep to hold fire enough for a whole night in cold 
weather. 

Grates should be proportioned to the heating 
surface of the building (radiating surface), which, of 
course, is proportional to the water to be evaporated 
or the steam to be condensed. 

Ordinarily, a pound of anthracite coal will evapor- 
ate ten pounds of water from the temperature of the 
return water to steam, at almost any pressure. To 
evaporate water — make steam — from water, at 178° 
Fahr., a fair temperature for return water, to one 
pound pressure of steam about 1,000 heat units are re- 
quired. This is low pressure. To evaporate the 
same water to 100 pounds pressure of steam it will re- 
quire 1,047 heat units. This will be for high pressure 
conditions. If, however, we still have high pressure 
conditions, and a very much hotter temperature of the 
return water than before (say a temperature of 225° 
Fahr. for the return water, which would be a natural 
condition with a high pressure gravity return appara- 
tus at 100 pounds pressure), then the heat to evapo- 
rate one pound of the return water to steam again at 100 
pounds will be still approximately 1^000 heat units, or 
the same as for low pressure steam. So that approxi- 
mately and for all ordinary usages, it is safe enough to 
say that one pound of water requires 1,000 heat units to 



GRATES AND CHIMNEYS. 115 

evaporate it, no matter what the pressure. With this 
in mind, we have the first essential item of data in 
finding our grate surface. Suppose we are going to 
evaporate 1,000 pounds of water in an hour, then we 
know we must burn about 100 pounds of coal in the 
same time — one hour — and this being fixed, we proceed 
to determine the size of the grate. 

It has been found by many experiments on Amer 
ican coal, that Avhen it is consumed at the rate of 
between 8 to 9 pounds per hour per square foot of 
grate, that the maximum of practical efficiency is 
obtained with ordinary grates and boilers. This seems 
to establish at once the grate surface that should be 
used, but in this we would be incorrect for all pur- 
poses. For high pressure boilers, with a fireman in 
attendance, it has been established, empirically, that 
one square foot of grate should burn 15 pounds of coal 
in the hour and this is generally the proportion used 
in common boilers, where the conditions of draft, etc., 
is not known. But for house heating boilers this will 
not do. It is not the question of whether a certain area 
of grate to a given weight of coal gives the greatest 
efficiency per pound of coal, but it is a question of 
preparing a grate and furnace that will hold coal 
sufficient for a night's burning without further attend- 
ance, than to clean and fill the furnace at bedtime 
and find steam in the morning at 6 or 7 o'clock, with- 
out unnecessary waste of fuel. This is the condition 
presented in house heating, and it is for this we must 
proportion a grate and furnace in a heating apparatus. 
If we are to evaporate 300 pounds of water every hour, 
from 10 P. M to 7 a. m. (9 hours), we know we must 
burn at least 270 lbs. of coal during the night. A 



116 STEAM HEATING FOR BUILDINGS. 

quantity of anthracite coal of this weight will be from 
7 to 8 cubic feet in bulk, and if we give it a depth of 
one foot over a grate, it will require a grate surface of 
from 7 to 8 square feet. A fire 1 foot thick is a deep 
fire, but as it is to burn so slowly, sufficient air will 
pass through it with any ordinarily good draught. 
Even if it had to be 14 or 15 inches thick, to run a 
couple of hours longer, this probably would not mat- 
ter ; so that we have established a fact that in this 
class of cases our grate must be, say, 8 square feet 
superficial area to burn 270 pounds of coal in 9 hours, 
or 30 pounds of coal per hour, giving us a ratio of 
one square foot of grate to each 3f pounds of coal 
burned per hour. Now practice has demonstrated 
that a rate of combustion of about 4 pounds of coal 
per hour per square foot of grate is a proper and 
reasonable consumption for house heating boilers. 
Less grate area may do with a good draft and thicker 
fires, but the chances are against efficiency in coal 
consumption when the 4 to 1 limit is passed, that is, 
when more than 4 pounds of coal per hour are 
burned. With this proportion of grate to coal, the 
accumulated ashes will not prevent the passage of the 
proper quantity of air as the time for firing again 
approaches, and it may safely be relied upon. 

The amount of air space in a grate must not be 
overlooked. If the air space is contracted or very 
fine, more intensity in draft is required. This is why 
some apparatus does better with one style of grate 
than with another. The total area of the grate may 
be near the regulation size, but the air space is not 
sufficient or it is of such a nature that it becomes 
choked with the ashes and clinker too readily, thus 



GRATES AND CHIMNEYS. 117 

the openings in any grate must be sufficiently large to 
pass the greatest quantity of air required when the 
fire is packed with ashes, as in the last hour it is sup_ 
posed to run without attendance. Smaller openings will 
not answer, and any much larger are unnecessary, al- 
though there is considerable scope in this latter respect 
as it is the constant opening or closing of the draft- 
door which really regulates the quantity of air required 
by the fuel, provided it is ample in the first place. 

Chimneys. — The question of the chimney should 
be considered with the subject of grates. There are 
two requisites for all chimneys : First, a chimney 
must be able to pass air in sufficient quantities to 
consume the coal, and, second, the intensity of the 
draft must be equal to passing the required quan- 
tity of air through the fire, no matter how much ashes 
there may be on the grate nor how thick the fire may 
be. The size of the coal used may be changed so as 
to favor a low or poor intensity of the draft, but 
should the air supply be insufficient in quantity, in- 
tensity will do very little to make it up and the result 
will be insufficient steam or no steam, and a constant 
poking of the fire without satisfactory results. Coal 
will burn in an open grate or on the hearth, but the 
rate of combustion cannot be controlled, and the mass 
simply burns from the outside unless the blower is 
used. A chimney 40 feet high will generally have the 
required intensity, but this same chimney may be so 
reduced in volume by bad turns in the wall, or by 
insufficient area in any part of its length or its 
whole length, that it cannot burn the coal required, 
and therefore is useless. It sometimes happens that 
the chimney has just about the cross-sectional area 



118 STEAM HEATING FOR BUILDIN08. 

that will do the work under favorable conditions of 
weather and fuel. These are the worst kind of chim- 
neys. They pass muster under the favorable condition 
of affairs, and fail entirely in damp and cold weather, 
or with unfavorable fuel, such as the harder kinds of 
anthracite coal, when with the free burning coals they 
can be just made to work by watching them. When 
a chimney proves itself entirely too small, it is, of 
course, improved by enlargement or by an increase of 
height, though in the latter direction much is not to 
be expected from an increase of height of 10 or 15 
feet, as the velocity of draft increases very slowly 
indeed with the increase of height of the chimney. 

It is well to remark that a chimney may be too 
large in diameter, though this does not often occur. 
Still I had a 12 X 36 inch chimney, of about 40 feet 
high, into which a small boiler with about 400 feet of 
radiating surface connected. 1 found it necessary to 
divide this near the middle by a wall, leaving a 12 X 16 
inch flue for the boiler, before satisfactory results were 
obtained. The amount of heated gases passing into 
the large chimney was not enough to cause a move- 
ment of air through its whole section, so that the 
intensity became almost nothing, and the conditions 
were not much better than passing a stovepipe through 
a hole in a wall into an area or light shaft. 

Thus the chimney must be capable of passing suffi- 
cient air for the greatest consumption of fuel ever 
likely to be used in the apparatus. Less air will not 
do. More than is needed does no harm, for it is 
within the power of the operator or the automatic 
draft regulator to diminish the quantity of the air. 

An old rule is that the area of a chimney should be 



GRATES AND CHIMNEYS. 119 

not less than one-eiglitli the area of the grate. If this 
rule Avas correct, or nearly correct, for mill chimneys, 
it cannot blindly be applied to chimneys in private 
dwellings, though, on the other hand, if a designer 
has no better guide, it may be followed with some 
degree of surety. 

But the 1 square foot of chimney area to 8 square 
feet of grate, as applied to high-pressure boilers, 
where the consumption of fuel is about 10 pounds of 
coal to a square foot of grate, will not do in all cases 
where the consumption of coal falls to as little as 4 
pounds per foot of grate, or the 1 to 8 rule would 
result in an enormously large chimney. 

Suppose the case of a hospital or school with a 
chimney 100 feet high, arranged on the gravity auto- 
matic principle, the intention being to keep a fire over 
night without attendance, in which the grate area 
might be from 80 to 100 square feet, the 1 to 8 rule 
would be a chimney out of all proportion to the size 
and actual requirements of the building, though in the 
case of a large private residence where the total grate 
area would be only 8 square feet, a chimney of 1 
square foot, 40 to 50 feet high, w^ould be eminently 
proper, as such a size Avould be required to give a 
practical magnitude to the chimney. 

The proportion of frictional surface in a small 
chimney is very much greater than in a large chimney, 
and thus the 1 to 8 rule will do very well in chimneys 
for house work, or where the chimney seldom exceeds 
40 feet in total height. In very small apparatus, how- 
ever, the 1 to 8 rule may not prove ample. Take a 
gL'ate of 3|- square feet ; under the 1 to 8 rule the 
chimney will be 8 X 8 inches. Now an 8 X 8 inch 



120 STEAM HEATING FOR BUILDINGS. 

chimney is usually enougli for the ordinary American 
stove, but short 8x8 inch chimneys often fail to give 
the required draft for a steam heating apparatus 
with a grate of 3 to 4 square feet. If the chimney is 
built smooth and straight, and 30 to 40 feet high, it 
may prove just ample, but if it is drawn over two or 
three times, to carry it around fireplaces at the dif- 
ferent stories, and roughly corbled on the inside with 
chimney pots and other apparatus on its top, the 1 to 
8 rule may prove very deficient. 

An 8 X 12 inch chimney is the smallest that should 
be built in a house for, a heating apparatus, though 
not because it may actually require that size chimney 
for the combustion of the coal, but to give a practical 
magnitude for roughness and want of cleaning, etc., 
and no other pipe or flue should be taken into it 
except the boiler flue. 

For apparatus, such as are put into large mansions, 
which burn 40 to 50 tons of coal in 180 days, a 
12 X 16 inch flue is little enough for the above reasons. 

Care in building a chimney is necessary, as a 
smooth chimney will give a better draft and keep 
clean longer than any other. Offsets in chimneys 
should be avoided, and equilateral and parallel 
sides are best unless the chimney can be round. 

To those who are interested in large chimney con- 
struction I would recommend R. M. & F. J. Bancroft's 
practical treatise (Jno. Calvert, publisher, Manches- 
ter, Eng.), where theoretical formulas are given, 
together with illustrations of many large chimneys, 
with the results of experiments obtained therefrom. 

The intensity of a chimney, due to its height^ and 
heat, is usually represented by inches of water. For 



GBATES AND CHIMNEYS. 121 

instance, a chimney 100 feet high, warmed until the 
bulk of its gases has been doubled, or the density of 
the air in the chimney reduced one-half, will have an 
intensity or power nearly equal to three-quarters of 
an inch of water. Eemember, however, that this 
intensity of three-quarters of an inch head of water 
can only be obtained in such a chimney at the moment 
the damper is shut and the flow of air checked in the 
chimney. When the damper is open and the air or 
gases passing freely through the chimney, another 
condition of intensity exists much less than the 
former, and which may fall to a third or quarter of it, 
or even less, only one-tenth, according as the chimney 
is passing less or more air. The theoretical intensity 
in a chimney 100 feet high, in which the gases have 
been doubled in bulk by raising their temperature 
500° Fahr., will give a theoretical velocity of about 
112 feet per second in the middle of the chimney, but 
as this 112 feet per second is dependent on the in- 
tensity, and as the intensity begins to decrease the 
moment the air begins to move, a new condition 
follows; the intensity becoming less and quantity 
greater. This may be called the practical efficiency 
of the chimney. 

This practical efficiency constantly changes in chim- 
neys, depending on their height, temperature, area, 
and shape. 

It is of more importance to us, therefore, to be able 
to discover the practical efficiency of a chimney, or, 
more properly, to construct a chimney that will give 
us a desired efficiency, than to find the theoretical 
velocity or intensity, as they both vanish in practice 
and resolve themselves into the third condition (prac- 



122 STEAM HEATING FOR BUILDINGS. 

tical efficiency), which is the one we are interested in. 
The friction of the chimney is the largest and most 
important factor in producing this condition. It is 
the retarding factor, although the weight of the hot 
gases, compared to the colder outside air, that pass 
through the chimney are the accelerating factor. The 
theoretical velocity must form the basis of the theo- 
retical quantity, but this is figured on the difference 
in weight between two columns of pure air without 
moisture, forgetting there is carbonic acid gas and 
unconsumed carbon in one of the columns. Now our 
chimney flue in practice is filled with a composition 
of air, carbon, etc., that has a greater specific gravity 
than air. Pure air is composed principally of 77 per 
cent, of nitrogen and 23 per cent, oxygen (by weight), 
and at a temperature of 60° a bulk equal to 14 cubic 
feet will weigh a pound under the ordinary conditions 
of our atmosphere. About 11 to 12 times this quan- 
tity of air is necessary for the theoretical combustion 
of one pound of coal, though in practice it runs up to 
17 or 18 times that quantity, and sometimes as high 
as 20 times, with poorly brick-set boilers. 

The practical efficiency of a chimney may be meas- 
ured by a water-gauge when the apparatus is in full 
operation, with the dampers wide open while passing 
through the fuel the full quantity of air required for 
proper combustion, so that the gases of combustion, 
instead of being of the same weight as common air, 
will be about one-twelfth heavier, reducing the the- 
oretical efficiency considerably. The friction in the 
chimney, the friction of the smoke pipe and its turns, 
the friction of the boiler and its flues, and the friction 
of the air through the grate and its bed of fuel, all 
tend to cut down the theoretical velocity and intensity 



GJRATE8 AND CHIMNETa. 123 

so much that a very high factor for safety must be 
provided in a chimney constructed by theoretical 
rules. Still, without theory much could not be done. 
It establishes safe comparisons and an ultimate limit 
beyond which it is impossible to go without using 
mechanical power to increase the velocity of draft. 

Presumably, if any rough rule Avas advanced for 
chimneys, it would not be safe to assume a greater 
intensity than one-tenth the theoretical value, and for 
small chimneys that would probably be too great. In 
a chimney 100 feet high, warmed about 500° above 
the outer air, the intensity is about 0.75 of an inch of 
water, and the velocity corresponding thereto, about 
112 feet per second in the chimney, and about half 
that, or ^^ feet per second through the ash door, if 
equal area with the chimney, as the air is about 
double the density and half the volume before it 
passes tnrough the fire. Now, for an intensity of 
one-tenth, or 0.075 of an inch of water, the flow of 
gases in the chimney will be about 38 feet per second, 
and at the draft door about 19 feet per second, or a 
practical efficiency of about one-third. These are 
high practical efficiencies and are not to be obtained 
in small crooked chimne3^s built into the walls of a 
house and often into wet or damp outside walls. 

The theoretical intensity of a chimney may be 
obtained and remembered in a practical way as fol- 
lows : One pound of pure air fills 12.387 cubic feet at 
a temperature of 32° Fahr. This will make a column 
of air of one square inch 1,783 feet high, which, of 
course, will exert a pressure at the foot of the column 
of one pound per square inch. We never, however, 
have to do with so great a pressure in an ordinary 



124 STB AM HEATING FOU BUILDINGS. 

chimney draft as one pound, but we liave to work 
with ounces or inches of water. The ounce of pres- 
sure will sustain a column of air lll^^^ths feet high 
(which for easy remembrance may be called 112 feet), 
and an inch of water j^ressure will sustain a column 
of air ^Q feet high or two-thirds of 100. feet, which 
is also easy of remembrance. If we increase the 
temperature of the column of air 490° Fahr. we double 
its height and make its density only -J, or,if instead of 
increasing its temperature 490° Fahr. we increase it only 
245° Fahr., we increase its height one-half, or 33 feet, 
making the equivalent height of the column 100 feet. 
Now this is an ordinary condition for the chimney of a 
low pressure steam apparatus. The gases are at a tem- 
perature of from 250° to 300° Fahr. as they enter the 
chimney, and the density of the column of air, though 
it is 100 feet long, is only equal to the density of a 
column a little over QQ feet long at the outside tem- 
perature. Now it is the difference in height between 
these two columns that gives the data for the velocity. 
This difference, called liead^ or difference of height, is 
33 feet, and the velocity of the air as it enters the flue, 
due to such a height, will be the same as a stone would 
have in that part of its travel when it reached 33 
from the point it first fell from. This being known, 
the remainder of the calculation is easy, it being 
simply to find the velocity of the stone by the rule 
V = l/H X 8, in which Y is the velocity looked for 
and H the height in feet fallen through, and 8 
half the distance fallen through in a second of 
time. Our height being 33 feet, the square root 
is 5.75 feet, which multiplied by 8 gives 46.92 feet 
as the theoretical velocity per second. The col- 



Q RATES AND CfflMNEYS, 



125 



umn being warmed and expanded one-half its original 
length, the intensity will be one-half the original 
weight. 

If we have a chimney still 100 feet high and we 
warm the gases until they are double their bulk, then 
the density is -J, and the head or height one-half the 
chimney. The chimney being 100 feet, H is 50 feet, 
square root of which is 7.07, which multiplied by 
8 gives 49.56 as the theoretical velocity — not a very 
large gain for an increase of about 245° Fahr. in the 
temperature of the chimney gases. 

In practice I do not dare to give the ordinary 100 
feet stack a greater efficiency than that due to a 
velocity of 25 feet per second, and when the walls of 
the building will admit of good nearly equilateral 
chimneys I figure it on the basis of 15 feet per second, 
with the bulk of the gases taken at 600 cubic feet per 
pound of coal. 

As the subject of grates and chimneys is treated 
together I will again refer to grates before finishing 
the chapter, as the same order was carried out in the 
earlier editions of the book. 



Diameter of Round 


Square Feet of 


Diameter of Round 


Square Feet of 


Grates in Inches. 


Surface in Grate. 


Grates in Inches. 


Surface in Grate. 


lU inches. 


1 feet 


26i inches. 


3| feet. 


15 


n- " 


27^0 " 


4 " 


m " 


n " 


28 


41 ., 


18 


If " 


28| " 


4i " 


19t% - 


2 " 


29i " 


43 .. 


m " 


It :: 


30i " 


5 " 


21i " 


31 


5J " 


22i " 


2f " 


31| " 


54 " 


,23i - 


3 " 


32i '• 


5f " 


'24i " 


U " 


33^ " 


6 " 


25J " 


3j " 







126 



STEAM HEATING FOB BUILDINGS. 



The preceding table gives the number of inches in 
diameter for circular grates, from one square foot to 
six, inclusive, advancing by one-quarter of a square 
foot, and will do for ready reference by the fitter. 




Fig. 55. 



Fig. 56. 




Fig. 57. 



Fig. 58. 



Why do grates break? Bound grates made of 
concentric rings and straight radial arms always 



GRATES AJSri) CHIMNEYS. 127 

break and fall to pieces, never wearing out in tlie 
ordinary way. There is usually the same result with 
parallel bars, confined with a ring, and they are the 
two forms most likely to be made by any one who is 
required to get up patterns and has not had experience 
in the matter ; since the pattern for the straight-barred 
grate is so much easier to make. The reason for its 
breaking is because the thrust of the straight parts of 
the grate is not compensated for when expansion 
takes place, and a rupture of the outer rings is the 
result. 

In this matter it would be well for the engineer to 
take pattern from the stove manufacturer, and follow 
him in this respect. No straight bars are here used 
in circular grates, as a rule ; or, if one has to use 
straight bars, they are short and unconfined at one 
end, radiating in or out. 

The same princi]3le applies to all grates. The old- 
fashioned three-barred common grate fails by reason 
of the ends dropping off when least expected, due to 
the unequal thrust of the bars against their ends, 
quietly cracking them in the angles, where they are 
the weakest. Figs. 55 and 56 show grates that will 
crack ; Figs. 57 and 58 show grates which will not 
crack, if very sharp corner angles are avoided by 
rounding them a little. 

Shaking grates have taken the j)lace of common 
grates in nearly all styles of heating apparatus, and 
in the latter part of the book the subject of grates 
will be taken up again and gone into more in detail. 



CHAPTEK X. 

SAFETY-VALVES. 

Every boiler, for the generation of steam, for 
power or heating, must have a safety-valve. 

A perfect safety-valve is a desideratum, for with a 
valve of sufficient area that will respond to the de- 
sired pressure of steam an explosion from over pres- 
sure would be an impossibility. 

The primary use of a safety-valve on the steam 
generator is to relieve an excess of pressure, but, 
aside from that, the noise that it produces when 
the steam is escaping makes this an auxiliary to the 
pressure-gauge by indicating that the maximum pres- 
sure has been reached, and that immediate attention 
of the engineer is required, if not in the interest of 
safety, at least in the interest of economy. 

A safety-valve, to be sufficiently large, should be of 
such proportions that it will let all the steam escape 
which the strongest fire is capable of producing when 
all the other outlets of the boiler are closed, and for 
house boilers particularly the safety-valve should be 
calculated by a rule based on the greatest evapora- 
tion, 

128 






SAFETY VALVES. 129 

Engineers who have giyen sizes for power boilers 
have not considered this question in relation to house 
boilers, and nearly all have a different rule for the 
questions ihej have considered, with frequently very 
different results. 

To a steam-fitter looking for information on the 
subject, and v/ho is confessedly ignorant of the prob- 
lem, this diversity must raise doubts as to the authen- 
ticity of some of the methods, and he is liable to be 
guided by the general reputation of the writer as an 
engineer, and take it for granted that his rule is 
applicable to all cases, and apply it to house-heating 
purposes. 

All boilers should have ample safety-valves, but 
house boilers Avliich are automatically governed and, 
as is customary, left for long periods without any one 
near thom, the safety-valves will be the sole regula- 
tors, should tlieir regulating doors fail, and conse- 
quently they must have proportions beyond a doubt 
as to their efficiency. 

Many boilers burst when working at their ordinary 
'pressure, and mysterious unavoidable causes are often 
assigned as the reason ; but there is only one reason — 
insujjicient strength, and that either from a defect of 
construction, or by deterioration of the material, or 
burning through neglect ; and in a case of this kind 
no safety-valve can respond, the valve being set for a 
higher pressure than that at which the boiler ex- 
plodes.* 

* I have entered boilers where pins were out of braces, and braces 
broken ; and one case where the mud deposit in a horizontal boiler covered 
four rows of tubes at the back end, cracking and bulging the shell, the 
J)ank of njud apparently holding the boiler together, 



130 STEAM HEATING FOR BUILDINGS. 

The office of the safety-valve being to relieve 
the boiler of pressure above its ordinary working 
pressure, it must be large enough to let the greatest 
quantity of steam ever likely to be made escape freely. 
In proportioning safety-valves for small boilers, 
and, in fact, for most boilers, the size is frequently 
simply guessed at ; the engineer or fitter pats on a 
valve of certain size, because he is in the habit of 
doing so, or because some former employer did it, 
having in mind the while an idea that if a certain 
size pipe carried all the steam the boiler could make 
to the engine, a safety-valve very much smaller in area 
would answer, since it escaped into the atmosphere 
only — not knowing that a two-inch safety-valve blow- 
ing off at 60 pounds had an opening so small that if 
it was round he could not put his pencil through it. 

When a valve begins to blow off, the pressure 
underneath the center of disk decreases out of all 
conceptional proportions to the pressure in the boiler ; 
the decrease not being due to a diminution of the 
pressure in the boiler (as the steam may actually be 
increasing), but to the draught caused by the escape. 
The laws of the phenomenon are imperfectly under- 
stood, but the results have been conclusively con- 
firmed by Professor Trowbridge and others; the pro- 
portional difference being greater for greater pressures. 
Professor Burg, of Vienna, found by actual 
experiments with an apparatus constructed for the 
purpose, that a valve of 4 inches diameter raised 
from its seat when blowing off, according to the two 
first columns of the following table. The last two 
columns are calculated that the fitter may form an 
actual conception of the openings by comparing then^ 
to something he is perfectly acquainted with. 



SAFETY VALVES. 



131 



The first column gives the pounds per square inch ; 
the second, the actual lift in fractions of an inch ; the 
third, the actual size of openings in decimals of a 
sauare inch, when the bevel of the valve seat is 45 
degrees ; and the fourth^ the internal nominal size of 
gas pipe nearest the actual opening. 

TABLE No. 2. 



1. 


2. 


3. 


4. 


Prebs. 


Lift. 


Area. 


Pipe. 


13 


-h 


.25 


L 


20 


-h 


.187 


f 


85 


-h 


.166 




45 


-eh' 


.137 




50 


-h 


.1048 


1 


90 


ih 


.0534 


i 



The following graphic illustration has been 
made to show at a glance the size of the openings : 






H 



w © 




ACTUAL SIZE, 



132 STEAM HEATING FOR BUILDINGS. 

The large rim incloses the area of a 4-iiich disk 
(12.56 square inches), and the smaller ones the areas 
of the openings at the different pressures. 

It can be seen from the foregoing that an increase 
of pressure lessens the size of the opening ; nor do 
the increased pressure and flow of the steam compen- 
sate for the decrease in the size of the opening, and 
what is required is a valve of very great diameter, or 
one that will open nearly its full area. 

There are many formulas for calculating the 
size of safety valves, all based on the size of the disk ; 
and, though arbitrary, they may be useful, as they give 
sizes about four times the area of ordinary practice. 

Fairbairn allows 29 square inches for a 50-horse- 
power boiler. 

This valve is nearest to what can be purchased as a 
six-inch valve. When we take into consideration the 
variations in formulas for velocity of flow of steam 
through apertures, that these velocities are based on 
the efflux through round holes or conoides, that the 
lift of the circular six-inch disk must be sufficiently 
great to allow an annular opening equal to f of a 
square inch, and perhaps as great as 1-J square inches 
for a pressure of 50 pounds above atmosphere, should 
the conclusions be correct which we draw from the ex- 
periments of Prof. Burg with a four-inch valve (vide 
Trowbridge, " Heat Engines "), we are not sure that it 
is possible to get an opening equal to the smallest 
above mentioned. 

Eankine says : " Divide the number of pounds of 
water which enters the boiler in an hour (to supply 
the loss by evaporation) by 150, and the product is 
the area of the valve in inches." 



SAFETY VALVES. 133 

Bourne says : " Multiply the area of the piston in 
inches by its velocity in feet per minute, and divide 
by 300 times the pressure of the steam, and the 
product is the area of the valve in inches." 

Another rule allows one-half a square inch of the 
disk for each square foot of grate, and though I am of 
the opinion that the opening in valves should be pro- 
portional to the grate surface, the question will arise 
why is not pressure taken into consideration, even 
assuming the half-inch of the valve area to be suffi- 
cient. But is it enough ? With ordinary boilers it is 
common to burn 10 pounds of coal per hour on a 
square foot of grate, and should the coal evaporate 
ten times its own weight of water (not an impossible 
thing) there will be 100 pounds of Avater evaporated 
to a square foot of grate in an hour, which will give 
a 50 H.-P. boiler about 30 square feet of grate and 15 
inches of area of valve. According to Zeuner, it will 
take 3000 pounds of steam about an hour and a quar- 
ter to pass through a hole with a section of one square 
inch when the pressure is 50 pounds. No four and 
one-half inch valve of com'mon construction (the 
nearest to 15 square inches of disk) can give such an 
opening, and the more I consider it the more I am 
inclined to repeat the words that " the ordinary 
safety-valve is only a danger signal." 

According to an act of Congress, for steam-boats, 
etc., boilers with stayed furnaces are to have 30 
square inches of disk area for every 500 feet of effect- 
ive heating surface, and for cylindrical boilers 24 
inches of disk for the same surface. The word effect- 
ive is here taken advantage of, and as a rule (by what 
authority it is difficult to understand) that about two- 



134 STEAM HEATING FOB BUILDINGS. 

thirds only of all the surfaces of marine boilers is 
considered effective. Thus, if we add 250 to the 500 
mentioned, we again have what might be called a 50 
horse-power boiler, with 30 inches of disk or a little 
more than a six-inch valve. The law also regulates 
the size of "lock-up" valves at two inches diameter 
of disk for 700 feet of effective surface or less ; three 
inches for 1,500 feet, four inches for 2,000 feet, five 
inches for 2,500 feet, and six inches for any boiler 
longer. Such valves, of course, are not expected to 
do much more than sound an alarm. 

Rules which are based on the work done in an 
engine cannot be applied to boilers in apartment 
houses and stores, in which, though the latter have 
engines frequently, and both have large pumps for 
hydraulic elevators, the steam used in the cylinders 
seldom represents more than one-third of the water 
evaporated, the remainder being for warming, cook- 
ing, washing, drying and other purposes. Again, 
rules based on evaporation, which do not take pres- 
sure into consideration, must be carefully sifted, and 
none used that will not provide for the taking away 
of all the steam at all ranges of pressure. Should a 
valve be found upon experiment to be just sufficient 
to relieve a boiler at 100 pounds of steam, the 
same valve would not do for ten pounds maximum 
pressure. 

According to the relative volume of steam, at half its 
theoretical velocity when flowing into the air, two square 
inches of actual opening of valve should be ample for 
the number of cubic feet of water evaporated per 
minute at the different pressures given in the follow- 
ing table ; 



SAFETY VALVES. 



135 



Pressure in Boiler above i Cubic Feet Water Evapo- 
Atmosphere. rated per Minute. 



1 

25 

50 

100 



.25 

.80 
1.25 
2.13 



Actual Size of Opening ir 
Valve. 



2 square iuches 
2 " 
2 " 



The J cubic foot of water per minute is equivalent 
to about a 30 horse-power boiler, and the others are 
respectively 100 horse- power, 150 horse-power, and 
250 horse-power ; and two square inches is the small- 
est safe area of opening that will keep the steam 
down to the pressure in the first column. Of course, 
if we can get the theoretical velocity of flow, about 
one square inch area will do ; but there is no factor 
for safety to cover friction under the valve, in the 
escape pipes, etc. 

By a study of the above, it will be seen that if a 
boiler is of such construction that 25 pounds of steam 
is the maximum, it will require a larger valve for the 
same amount of water evaporated than a high pres- 
sure boiler, and that indiscriminate rules are not to 
be used. 

Theoretically, a safety valve will require ten times 
the area for 1 or 2 lbs. pressure that it will for 100 lbs. 
pressure. 

There has been much effort to obtain a safety valve 
which will give a large opening, and in some instances 
valves thus made have proved practically a success, 
though not in general use, since the necessity for them 
is not recognized by the pubUc, who content themselves 
with a danger signal, where the noise it makes when blow- 
ing off is all that can entitle it to the name of safety valve. 



136 



STEAM HEATING FOR BUILDINGS. 




Fig. 59 shows a common safety valve, with an aux- 
iliary attachment, which is capable of pulling the 
valve open to its full extent. A is an ordinary safety 

valve, put on in the 
regular way ; ^, a com- 
mon low-pressure dia- 
phragm or regulator, to 
be described later, at- 
tached to the end of 
a the lever, and suitably 
fastened to- the boiler 
with the pipe connec- 
tion C, to the under side 
of the diaphragm, and 
taken from the water 
space of the boiler, for 
two reasons, — namely, 
that the water in the 
pipe may be cold, so as not to affect the rubber of 
the diaphragm. The water being steady and solid 
prevents vibrations, and gives the initial pressure 
unaffected to. the underside of the rubber. Fig. 60 
shows the same apparatus in a position when blow- 
ing off, the pressure under 
the rubber overcoming the 
weight on the lever. 

When steam begins to 
escape, it cannot affect the 
diaphragm until the pres- 
sure in the boiler falls, 
when the diaphragm sub- 
sides. 

This same principle can 
be applied to high pressure safety valves by using a 



Fig. 59- 




Pig. 6o, 



SAFETY VALVES. 



137 



diaphragm, especially constructed, as in high pressure 
damper regulators. 

The escape pipe D, Fig. 59, of the safety valve, is 
sometimes carried down and under the grate by 
steam-fitters, in order that the escaping steam may 
dampen the fire, and check it by interfering with 





Fig. 6i. 



Fig. 62. 



combustion, a point worthy of consideration by all 
engineers. 

Another arrangement for very low pressure is a 
water column, connected as in Fig. 61. A connection, 
A, is taken from the steam space, and carried down 
and up, forming an inverted siphon filled with water. 



138 STEAM HEATING FOB BUILDINGS. 

When the pressure in the boiler exceeds the weight 
of the column of water in the pipe, it blows it out, let 
ting the steam escape, which will blow until the steam 
is all gone, or the pipe again filled with water. 

A modification of this principle has been con- 
structed, by which steam can be carried to about 12 
pounds per square inch, in buildings of ordinary 
height. A cylinder of any suitable construction is 
connected to the boiler, as shown in Fig. 62, and 
filled with water ; the pressure of the steam through 
the pipe a on the surface of the water in the 
cylinder presses it up in the pipe b ; but when the 
pressure is great enough to send the water over into 
the pipe c, the steam escapes at d. This arrangement, 
like the one before, will not stop blowing without 
manipulation, it being necessary to close the valve e, 
and open the valve /, to let the water again into the 
cylinder. 

A boiler with this arrangement on it, should also 
have a common safety valve set at a lower pressure, 
to give warning, for should this start to blow off, and 
be neglected, it will waste water and steam from the 
boiler. The pipe a may be long, so as to have the 
cylinder a considerable distance from the boiler ; in 
one case where it was set against it, the heat evapo- 
rated the water from the cylinder. 

A boiler with a safety water column on it, as de- 
scribed, should have a vacuum valve also, to prevent 
the water from being drawn into the boiler when steam 
goes down. 

Another arrangement which has been tried with 
some success, is an ordinary safety valve of large size, 
with a pipe a carried from the under side of the disk 



SAFETY VALVES, 



139 



down into tlie water in tlie boiler, as shown in Fig. 
63 ; the orifice of the valve forming an annular space 
around the pipe. 

The principle of this valve is that the pipe beiDg 
carried down into the water represents a certain area 
of the disk, which should be of scarcely any value 




when blowing off, but by being in the water the pres- 
sure underneath is not relieved. 

Pop-safety valves with differential disks and seats 
are also used for high pressures, by which very much 
larger steam passages can be secured than with ordi- 
nary valves of the same diameter. Details of some 
safety valves will be given in one of the latter chapters 



140 STEAM HEATINO FOR BUILDmOS. 

of the book. There are pop-safety valves on the 
market that will open and blow down a boiler in a few 
minutes, not only letting the excess of steam escape, 
but capable of allowing all the steam the boiler is 
capable of making, escape freely. 

Another point of interest to a fitter is an easy 
method of finding the weight necessary for a safety 
valve. 

j If they reason as follows they will always be able 
to find the required weight within practical limits and 
approximately correct. If the area of the valve disk 
is one square inch, it is only necessary to have a one- 
pound weight placed on the top of it (assuming itself, 
the disk, to have no weight ) to 1^ eep it closed against 
one pound per square inch of steam, and, of course, 
if the weight is 10 pounds it will hold the disk against 
10 pounds per square inch. This is substantially 
the " low pressure safety valve " with the weight on 
a spindle on the back of the disk ; the weight of the 
disk and of the " weight " having a total effect (with- 
out leverage, of the square inches of the valve multi- 
plied by the maximum j^ressure to be carried. But with 
valves having levers for high jDressures, wherein the 
weight must be fixed and kept within ordinary limits 
of size, the relative position of the weight to the disk 
must be considered, and the weight of the lever also. 

The lever always represents a constant resistance 
to the valve, and should be found first. For instance, 
with a disk of one square inch, with a lever of one 
pound, the lever being ten inches long, as shown, and 
the distance from the valve spindle to the fulcrum one 
inch, the lever will always exert the same pressure on 
the disk as a one-pound weight would, placed on the 



SAFETY VALVES. 141 

lever at lialf its length (five Indies). Thus it may be 
borne in .mind that the lever is a weight hung on an 
imaginary lever of half its own length and exerting 
pressure according to its weight. 

In this case, Avhere the lever is one pound, the dis- 
tance from the fulcrum to the spindle one inch, and 
the whole length ten inches, the lever will exert five 
pounds on the valve without a weight. But it is neces- 
sary to have a Aveight which is movable, as in Fig, 64, 
and suppose we have one of one pound also. If we 
placed this weight now on top of the spindle it adds 
just one pound to the force exerted by the lever 
(5 -|- 1 = 6), making the total pressure at that point 




10 11 12 13 14 

nii 20 221^ 25 £71^ 



Fig. 64. 

six pounds ; but if we move it the same distance from 
the spindle that the fulcrum is, only in the opposite 
direction (out on the lever), it vv^ill exert two pounds 
additional to the pressure exerted by the lever and 
will exert an additional pound per inch as it is moved 
from the disk, giving for the end of the lever 15 pounds 
and for the second notch seven. 

If, instead of a one pound ball or weight we have 
a 2j- pound ball, the pressure exerted by it will be 
the weight, 2|- pounds, multiplied by the distance to 
the first notch (2 inches), equal to 5 pounds plus 
5 pounds for the lever, making 10 pounds, or with 
the weight at the last notch, 2^ X 10 (= 25) + 5 = 30 
pounds. 



142 STEAM HEATINO FOB BUILDmOS. 

From tliis we get the simple formula A X P X D 
-j- W = B, in which — 

A is the area of the valve disk in square inches ; 

P is the pressure of steam in pounds per square 
inches ; 

D is the distance between the stem of the valve 
and the fulcrum ; 

W is the weight of the disk, stem and lever; 

B is the weight of the ball in pounds. 



CHAPTER XI. 

DRAFT REGULATORS. 

When the steam-heater wishes to govern any- 
thing automatically, his first thought is whether a 
diaphragm will answer, and if he can regulate what 
he wants with a rubber or hght metal diaphragm, he 
will never resort to a moveable piston, knowing the 
diaphragm will work until it wears out without getting 
out of order, and that a piston must be kept in the 
nicest of order to be depended on, since it is affected 
by corrosion and dust, while the diaphragm, being 
simple and cheap in construction, and having no 
delicate parts, will respond to small differences of 
pressure and will run for many years when con- 
structed and put on by one who understands it.* 

The steam-fitter uses it to regulate the ash-pit door, 
for the admission of the proper quantity of air to the 
fire in order to govern the steam pressure; to open 
the fire-door so that cold air is admitted through the 
furnace in case the draft-door is neglected (by leaving 
a clinker or lump of coal underneath the edge); to 
open the safety-valve, and sometimes to open a ''break 

* For high pressure, nicely fitted pistons have given excellent 
satisfaction for damper regulation. They will not do for very low 
pressures, however. 

143 



144 



STEAM HEATino VOB BUILDINGS. 



draft," an opening in tlie chimney. He also uses it 
for regulating the air supply to iii direct radiators, to 
govern tlie pressure of steam when expanding from 
high to low pressures in different systems, and to 
regulate water pressures. 

Fig. 65 shows a regulator of ordinary construc- 
tion, with a bowl at the top and bottom of the dia- 
phragm, in which A is the bottom bowl, to which the 




Fig. 65. 

support and pipe are attached ; B, the upper bowl, to 
which the fulcrum and lever are attached ; C, the 
diaphragm ; I), the fulcrum ; E, the lever ; and W, the 
weight ; the pressure under the diaphragm being the 
operating force. 

In constructing regulators, sharp edges of the metai 
should not be left to cut the rubber. The corners of 
the bowl at a' should be nicely rounded, and the 



DRAFT REGULATORS. ' 145 

flanges around the edge should be deep, to give room 
for the bolt holes, so that they will not be too near 
the inner edge. The standard F should not be riveted 
to the rubber, but rounded on the bottom to lay on it; 
nor should there be holes made in the rubber for any 
purpose inside of the holes in the flanges. 

Common flat rubber does not make a good dia- 
phragm; it should be of extra good quality, thick, 
and dished to fit the bowls; so that when inflated, 
there will be no tension on the rubber. 

Some makers leave off the upper bowl, using only 
a flange, but better practice recjuires the use of one, 
as it is nearly impossible then for over-pressure to 
burst the rubber when supported by the iron over its 
whole extent. 

In the construction of a diaphragm for high pres- 
sure, which will not burst, it is necessary that a very 
small portion of the surface of the rubber should be 
unsupported at any time; and the movement should 
be small, requiring the use of a compound lever with 
an ordinary weight. 

Fig. 66 shows a high i^ressure draft regulator, with a 
compound lever, in which a very small movement of 
the disk A will give a movement of 6 inches or so at the 
end of the lever at B, without straining the rubber in 
the least, the slackness at C forming a concentric cor- 
rugation, which admits of all the movement necessary. 

In connecting diaphragms with the boiler, it is 
best to take the pipe from the water space, as shown 
in Fig. 59, at C. But when that cannot be done, it 
may be taken from the boiler dome or any other con- 
venient place, except tapping into a pipe, which 
already has a ^^ draft" on it (rapid passage of steam 



146 



STEAM HEATING FOR BUILDINGS. 



througli it) for in order to prevent irregularities of 
pressure it is necessary to liave the initial pressure 
constantly under the rubber. 

When it is necessary to take a steam pipe to a 
diaphragm, instead of a water-pipe, the pipe must be 
trapped in such a manner that it will fill with water^ 
and the capacity of the trap must be greater than the 
bowls of the diaphragm ; so the water that has tilled 
the trap and cooled therein, Avhen it is pressed for_ 
ward, will be sufficient to more than fill the bowls, 
thus always insuring cold water on the rubber. 




Fig. 66. 



Some will not put a valve in a diaphragm pipe in a 
private house, fearing it may be shut off by some 
meddler ; but this is a matter which must be left to 
the judgment of the fitter. A very good way is to 
use not less than a f pipe, and immediately under the 
regulator plug the pipe with iron, and bore a -J-incli 
hole through the plug. This hole will pass the w^ate 
rapidly enough for the regulator, and in case the rubber 
should burst, the flow of hot water will not be large. 

When the rubber is fitted into the bowls without 



STEAM HEATING FOR BUILDINGS. 147 

tension, it very seldom gets holes in it, and will give 
warning by leaking, but should it be tight it will give 
away suddenly. 

When regulators are attached to ash-pit doors, 
or to extra draft-doors, set in one side of the ash-pit 
(leaving the door-proper for the removal of the ashes 
only), the chain is fastened to the end of the lever 
marked G, Fig. 65, and to the door; care being taken 
in placing the regulator so that the chain will have a 
direct pull, and not interfere with the opening of 
other doors. When a regulator is attached to the 
fire-door, the other end of the lever should be used, 
and the regulator set a pound or so stronger than the 
draft-door regulator. 

It is not a good plan to make one regulator do both 
duties, by using each end of the lever, as the doors 
work too close together, and a waste of fuel is the 
result, by letting cold air through the furnace fre- 
quently; the intention being not to open the fire-door, 
unless as a last resort. 

85. Doors for regulators should be set at an angle 
of between 30 and 45 degrees from the perpendicular. 
When a door hangs perpendicularly with the hinges 
on the top (usual in such doors), the leverage changes 
as the door swings from the perpendicular, throwing 
a rapidly increasing weight on the diaphragm chain; 
but when the door is on a good angle the increase is 
not so rapid, and the door is positive in its action when 
closing, being hung further from its center of gravity. 

Doors should be planed to fit tightly, and hinges 
and edges should be so constructed that ashes will 
not lodge on or under them, so as to hold them open 
or prevent their free action in all directions. 



CHAPTER XII. 



AUTOMATIC WATER FEEDERS. 



The water feeders that are attached to low- 
pressure heating boilers, are simply regulators,— they 
have no power in themselves to force water into a 
boiler, and must be used in connection with water- 




Fig. 67. 

works, or a tank near the top of the house; the head 
of water supplying the requisite power. 

So far, there has been but one description of auto- 
matic water feeder used in connection with steam- 

148 



AUTOMATIC WATER FEEDERS. 



119 



heating, and though different makers modify the shape 
and the valve, the principle is the same. Fig. 67 is a 
very good representation, in which A is a cast-iron 
case of suitable design; B, a copper float, with buoy- 
ancy enough for the work, and sufficiently thick so 
that it will not collapse with the pressure; E, a lever 




Fig. 68. 

made of brass, to admit of bending; F, a fulcrum, and 
G, a valve, formed with a piece of hard rubber, inserted 
in the end of the lever, in connection with the nozzle 
H, which is usually of brass. 

Fig. 68 shows a modified form of water feeder brought 
into use some years ago, in which the float acts directly on 



150 STEAM HEATING FOR BUILDINGS. 

the valve^ and in which the valve is visible through 
the^ glass H. This is very desirable, as it allows the 
operator to observe the valve and feed-water when it 
enters, and enables hirn to detect either a leakage or 
a stoppage. With this valve the pressure of the 
water has a tendency to close the valve, whereas with 
that illustrated in Fig. 67 the tendency of the pressure 
is to open it and cause leakage. The pipes B C are 
the boiler connections and F P is the feed pipe. 

Copper floats in boilers under high pressure nearly 
always collapse; but for low pressure they have been 
constructed to stand very well, though occasionally 
they fill with water when not well made. 

Hollow copper ball floats are usually made of two 
pieces of copper hammered into hemispheres, and 
brazed together. If they could be hammered after 
brazing, they could be made very strong, but as the 
reverse is the case, and the heating to redness makes 
them very soft, there is nothing for the artificer to do 
but make them as thick as he can, without impairing 
their floating power too much. In the brazing of a 
ball together, it is necessary to leave a vent hole in 
one hemisphere, until the joint is thoroughly brazed, 
and then plug it up. A very good way to make floats 
for regulators, since they require some kind of a boss 
to fasten the lever to, is to put a boss on the inside 
of the hemisphere, as shown in Fig. 67, and bore a 
small hole through it, having the thread for the lever 
tapped tapering; this hole will answer for a vent 
while brazing, and when ready to be fastened to the 
lever, the thread in the boss and the thread on the 
end of the lever can be tinned with soft solder and 
screwed together cold, which will make a perfectly 



AUTOMATIC WATER FEEDERS. 151 

water-tight joint and not leave a partial vacuum in 
the ball, as would happen if the ball was closed in 
the fire. This vacuum forms a factor not generally 
taken into consideration, which will materially add to 
the pressure the float is subject to in a boiler. 

There is one point in the construction of water 
feeders which requires particular attention, — namely, 
the size of the hole in the nozzle, H, Fig. 67, which 
forms the valve. This hole should be small, and the 
higher the pressure of the water-works the smaller 
should be the hole. It will be seen by looking at 
the figure, that by the area of the hole in H, the total 
pressure of the water can be made to overcome the 
force exerted by the float. A J-inch hole is usually 
sufficient to admit all the water required; but if a 
larger hole is wanted, care should be taken that the 
ball has a preponderance; otherwise the valve will 
not set firmly to its seat, and the leakage will fill the 
boiler and prove a source of annoyance. This should 
be guarded against, for though it is not dangerous, it 
is disagreeable, and many fitters prefer to leave the 
feeder off on that account, since a straw, or the least 
dirt, will make it inoperative, and fiood the boiler in 
consequence. In fact, the practice of to-day is to 
omit the automatic water feeder.. When a boiler is 
sufficiently large to hold a quantity of water above 
its safe-water-line that will be equal to the amount of 
steam you require for the radiators of the building, 
the water feeder is not necessary with a gravity 
apparatus wherein all the water is returned to the 
boiler. 

When there are steam-traps to any part of the 
apparatus; which do not return all the water directly 



152 STEAM HEATING FOR BUILDINGS. 

into the boiler, the water feeder should be put on, un- 
less there is some one constantly in attendance to 
supply water by some other means. With a return 
gravity apparatus, it may, however, be dispensed 
with, for the operator by looking at the water once a 
day, and letting in a supply when necessary, is a bet- 
ter reliance. A positive ^^open and shut" feeder, 
under all circumstances, has yet to be invented. 

When a water feeder is used, the upper or 
steam pipe must not be taken as a branch from 
another pipe, such as the main steam pipe; it must 
be taken from the top of the boiler, steam header, or 
dome, and away from other large pipes. 

Special attention should be paid to the foregoing. 
A case which came under my notice was that of a 
large horizontal boiler with a water feeder connected 
to the dome, the water pipe entering the regular feed 
pipe. The feeder had a glass on it, similar to the 
water glass on the front of boilers, and this boiler also 
was furnished with an extra water glass, connected 
with the front tube sheet, in the ordinary way, the 
upper pipe being taken from very near the flange. It 
was noticed that the water in the feeder glass always 
stood about five inches higher than the water in the 
boiler glass, which led to an investigation; and it ap- 
peared that the water in the front glass was the true 
level. The upper pipe of the feeder was then taken 
from the dome, and tapped into the boiler shell, when 
both glasses showed the same level of water. 

This question of draft in pipes is of vast im- 
portance, and should receive more consideration than 
is usually paid to it, in connection with boiler appur- 
tenances however. 



AUTOMATIC WATER FEEDERS. 153 

The '^dancing" or fluctuations of the water in a 
gauged glass is sometimes caused by depression or 
^^ water-trap" in the upper pipe connection, or by the 
formation of steam in the lower connection. This action 
must not l^e confounded with the effect of draft. The 
effect of draft is to lessen the pressure on the surface 
of the Vv-ater so that the latter will show a deceptive 
level. AVater will never go in the glass below its level 
in the boiler, except momentarily, caused by a pul- 
sation; whereas there is great danger of the glass 
showing a level constantly higher than in the boiler; 
when a water column with long connections is used, 
that is now so much in vogue. 



CHAPTER XIIL 

AIR VALVE ON RADIATORS. 

The usual position for an air valve on a coil or 
radiator is near the return pipe. On a vertical pipe 
or loop radiator it is nearly always on the last pipe or 
loop, meaning by the last the part opposite the steam 
inlet, though in radiators with steam and return con- 
nections on the 'same end it is sometimes found near 
that end, though, in my judgment, it is better to have 
it opposite and furthest from the inlet, no matter 
where the outlet may be. 

With high pressure steam the position of the air 
valve is not of as much importance as with low pres- 
sure or exhaust steam, and as a radiator that will 
work with low pressure, will always work with high 
pressure steam, it is always best to provide for the 
low pressure conditions. 

In vertical tube radiators the valve is generally 
placed high up on one of the pipes, the lower end of 
which was sometimes run down within the base of 
the heater, to very near the bottom. This was done 
on the assumption that the air being heavier than 
steam, would be the first to go out by the air-vent, 
and is presumably correct in theory. But it often 
happens the first of the water of condensation does 

154 



AIR VALVES ON RADIATORS. I55 

not run off rapidly until the radiator is under the full 
pressure of the steam, when the lower end of this 
pipe will be covered with the water, causing the latter 
to rise within it by the pressure in the radiator, and 
ejecting it through the air-cock or valve, something 
that should be avoided on account of the unnecessary 
annoyance, if for no other reason. 

In single chamber heaters, and heaters made of 
pipes, having free passage top and bottom, the air 
valve is often put near the top, the weight of the air 
apparently not affecting the egress. 

It is better, also, to draw the air from a single pipe 
or a loop near the top, or, at least, not too near the 
lower end of the radiator, as the draft caused by the 
escape of the steam through a pet-cock will some- 
times raise water from the base of the radiator, so 
that the further from the surface of the water the air 
can be in a vertical radiator the better. 

The greatest difficulty exists in drawing the air 
from a flat coil when the return pipe does not run 
below the water lines, but permits live steam to enter 
the coil from the lower end, forcing the air toward 
the middle of the coil. Some steam-fitters put an air 
valve on a return-bend, at a point about ■§- the length 
of the coil from the lower end, but the result is often 
a disappointment. The best way in case of box coils 
and flat coils, is to carry their return pipes heloio the 
tvater line and place the air valve very near the return 
end, but so arranged as it will not draw the water from 
the return pipe, which it often does if placed directly 
on the side of the small-diameter return pipe. For 
this reason it is better placed on the lowest return 
bend near the return pipe, and any work so piped will 



156 STEAM HEATING FOR BVILBINQS. 

not be likely to prove troublesome in this respect ; for 
the current of the live steam is always from the steam 
to the return valve within the radiator. 

The idea of the air aliuays gravitating through the 
steam, and finding the lowest part of a heater com- 
posed of small pipes, is erroneous, unless the steam 
is let in on top, as it usually is with flat or box coils. 
In pipes of large diameter, air will separate of its own 
gravity and settle down. 

In what is called the atmospheric radiator, the 
steam enters on top with an air hole or air cock near 
the bottom to let the air out, and a drain or return 
pipe to carry off the condensation in the bottom and 
deliver it to a tank without pressure. Steam enters 
this radiator through a very small pipe, with a nicely 
graduated valve, which admits any desired quantity 
of steam, and which fills doionward, and permits a 
part, or the whole of the heating surface of the radi- 
ator to be used, and thus graduate the heat of the 
room by direct radiation. It may be likened to a 
balloon partially filled with gas, the gas always 
remaining in the top.* 

Air and steam mix within a heater to a certain 
extent and at certain pressures, this mixture being 
of unknown weight but always greater than that of 
steam of the same density. 

Steam at the pressure of the atmosphere, and a 
temperature of 212 Fahr., has a weight about one-half 
that of air at the pressure of the atmosphere, and a 
temperature of 34° ; but when the air is increased in 
temperature about 160°, or what it would in a low 

* These heaters cannot be used in a gravity return apparatus, but an 
apparatus of this kind will be described elsewhere in the book. 



Ain VALVES ON RADIAT0M8, I57 

pressure radiator in contact with steam, the steam will 
then be about two-thirds the weight of the air. 

Air valves are various in design, but may be 
separated into four kinds ; the old-fashioned pet- 




Fig. 69. 

cock, the compression thumb-screw valve (Fig. 69) 
and the automatic air valve, working by the deferen- 
tial expansion of two metals or other materials as 
shown in Figs. 70, 70a, 70& and 71, and the air valve 
similar to the last, in which there is a float that will 
close the valve without the intervention of expansion 
should water appear. Figs. 72, 72a, 73. 

The pet-cock needs no explanation, and may be used 
on rough or factory work, but should not be used on 
fine or house work, for a plug cock will not stay tight 
on steam work, and will leak on the floors and wet 
the ceilings. 

The compression wood handle air valve is much 
used, and is simply a small angle valve, with or with- 
out a stuffing-box, as shown in Fig. 69. 

The automatic air valve embraces nearly as many 
designs as there are manufacturers of heating ap- 
paratus ; but the principle used is the same in each 
instance, viz., the difference of expansion of any two 
metals that will stand the action of steam, one fo 
which has a greater co-efficiency of expansion than 
the other. The valve really becomes a metallic ther- 
mostat, which operates a little valve. 



158 



STEAM HEATING FOR BUILDINGS. 



Fig. 70 shows a simple form of this arrangement ; 
A being a strip of cast-iron; B and h strips of 
brass, set against shoulders on the cast-iron ; and 
G the valve and stem passing through holes in the 
bar &, and the cast-iron A, and screwing into the 
other brass {B), 

When heated above the temperature at which they 



r\ 







Fig. 70. 



Fig. 70a.. 



Fig. 705. 



are fitted, the brass expands more than the iron and 
forms a bow shape, as shown, and draws the valve to 
its seat; the dotted lines show its normal position, 
The stem, where it screws through the brass B, forms 
a regulator, which can be adjusted with a scre'W 
driver, applied to a slot in the valve. The outside D 
may be a piece of pipe, or a casting, with a boss on 



AIR VALVES ON RADIATORS. 159 

the side of it, to tap a small pipe into, so as to 
carry the vapor away, if required. 

Fig. 70a is another modification of the same prin- 
ciple. 

The outside case C is brass, the rod I iron, or some 
metal with considerably less expansion than brass ; 
the rod B of brass once more, and the center or valve 
rod of the same metal as the bar I. By this means 
two brass rods move in one direction and two iron 
rods relatively in the contrary direction. This is a 
compound differential apparatus to secure the re- 
quired movement, without too great a length of tube. 

Fig. 70& shows a form in which one metal only 





Fig 71. Fig. 71a. 

(brass) may be used, the rod not being expanded as 
much as the case, for the reason that they are out- 
side, and not in direct contact with the steam, though of 
course metals with opposite qualities are best. When 
the case expands, it presses on the thumb-screw at the 
top, forming a valve, the thumb-screw forming an ad- 
justment. The automatic valves so far shown are old 
styles not much met with now, and obsolete. One of 
them is not a desirable feature. 

The valve shown in Fig. 71 is an automatic air valve, 
made by Jenkins Bros., of New York. It was the first 
valve in which a plastic composition, that would stand 
steam and give a large coefficiency of expansion^ was 



160 



STEAM HEATING FOR BUILDINGS. 



used. It takes up a small space, being no larger than 
an ordinary compression air-cock, and is suitable for a 
high or low pressure steam. A is the end screwed 
into the radiator, and B a regulating screw holding an 
expansible plug C, D being the outlet tapped to connect 
with an air-pipe of the building. The plug C is of 
india-rubber, and other substances that have an incre- 
ment of expansion, its elastic end forming a close con- 
nection with the seat A. 

Fig. 71a is a more modern modification of this type 
of valve, in which the vulcanized rubber is tipped with 
a rotary adjustable metal piece, to prevent adhesion 
to the seat. It is known as the Monash No. 3. 






Fig. 72. 



Fig. 72a. 



Fig. 73. 



Fig. 72 shows the Van Auken valve. It is a float 
valve to guard against water and has the expansion 
principle to close with heat. The rod A is of rubber 
and other substances, the expansion of which closes 
the valve Y. Should the radiator be partially closed 
or the circulation of steam bad and water fill the radi. 



AIR VALVES ON RADIATORS. 161 

ator, it will pass into the chamber and hft the inverted 
open float B, thus closing the valve against the escape 
of water. A tube C is used to secure a communica- 
tion between the top of the air valve and the pipe of 
the radiator, so water cannot be held in the case by 
the formation of a vacuum. 

Fig. 72a (the Onderdonk) is in many respects simi- 
lar to the foregoing. The movement of the valve due 
to heat however, is secured by the change of shape in 
the loop-shaped spring A. It is composed of two 
metals, the one with the greater difference of expan- 
sion being on the inside. The regulation of the valve 
V is secured by the movement of the screw seat S. 

Fig. 73 is another modification of the float valve. 
The differential spring pinches on the cone and forces 
the valve to its seat. The crooked syphon pipe also 
assists the water to run from the case into the radiator. 

Fig. 73a shows the most recent and probably the 
most reliable expansion air valve on the market. It 
is known as the No. 5 Self-cleaning Monash Air Valve. 
It can be used for a vacuum system and can be adjusted 
without disconnecting the coupling under the valve, a 
matter of great importance when there are many radi- 
ators to be looked after. 

It will be noted in the illustration. Fig. 73a, that the 
different parts of the valve are referred to by figures. 
1 is a cap which must be removed in order to adjust 
the air valve. This cap is provided with a left-hand 
thread and with a hard composition seat, shown 
at 2. The hard rubber stalk, marked 5, w^hich by 
expansion and contraction opens or closes the air 



162 



STEAM HEATING FOR BUILDINGS. 



Valve, is rigidly attached to the brass piece at the 
top. The valve can therefore be adjusted by screw- 
ing the brass piece up or down in the thread marked 
3. The air valve is connected to the radiator 




Fig. 73a. 



through the opening marked 4, and it will be noted 
that even when the air valve is closed, steam 
from the radiator may still surround the hard rubber 
stalk. In some forms of air valves the steam is cut 



AIR VALVES ON RADIATORS. 163 

off from the hard rubber stalk as soon as the valve 
closes by expansion, but here the entire ^^ stalk" is 
subject to the temperature of the fluid within the 
radiator. This valve is called self-cleaning, since the 
valve seat is at the bottom and the tendency will be 
to wash dirt, etc., into the air Kne to which the air 
valve is connected. The union connection for attach- 
ment to the air line is marked 6 and 7. 



CHAPTER XIV. 

STEAM PIPE, SIZE, AREA, EXPANSION, ETC. 

Theee are two kinds of wrouglit-iron steam and 
gas pipe — namely, lap-welded and butt- welded. 

There is no lap-wielded pipe smaller than IJ inch, 
though butt- wielded pipe is made of all sizes, except- 
ing those of very large diameter. 

Lap-welded pipe is considered the best, although 
for sizes smaller than two inches there is little differ- 
ence. The butt-welded pipe is the most uniform in 
size, though it is apt to open in the seam by twisting. 

All the pipe and all fittings made in the United States 
and Canada are supposed to be of standard dimen- 
sions, so that the whole will be interchangeable.* 

Occasionally in old buildings pipe is found which 
is known as " old gauge," which is somewhat larger 
than the pipe now in use. 

The size of pipe is standard, but the standard 
is arbitrary ; the inside diameter being nearest the 
nominal size of the pipe, which it always somewhat 
exceeds. Small sizes are more disproportioned (as can 
be seen by reference to the table of " Standard Dimen- 
sions of Wrought-iron Pipe," or to the diagram of 
sizes of pipe). 

The threads on the ends of pipes should taper 
about -jig- of an inch for an inch in length of thread. 

* This is not absolutely so, but they are near enough for ordinary work, 
and with adjustable dies the fitter finds little trouble in correcting small 
errors of gauge. A committee of the Society of Mechanical Engineers of 
which I was a member, have secured the adoption of the Biggs Standard 
for pipe and fitting threads since the above was first written, and it is 
hoped that hereafter the threads furnished by the trade will be absolutely 
interchangeable, the Pratt & Whitney Co. of Hartford, having com- 
menced the preparation of the standard gauges. 

164 



STEAM PIPE, SIZE, AREA, EXPANSION, ETC. 165 



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16P STEAM HEATING FOB BUILDINGS, 

FIgo 74,— Diagram of Cross-Section of Wrought-Iron Pipe. 




ACTUAL SIZE, 



RELATIVE AKEAS OF PIPE. 

The yoiiiig steam-fitter has not always a just 
^nceptiou ol how the size of one pipe compares with 



STEAM PIPE, SIZE, AREA, EXPANSION, ETC, 167 



that of another, not knowing how rapidly the area of 
a pipe increases with an increase of diameter. 

When the diameter of a pipe is doubled, the area has 
increased fourfold, and if one pij^e has one-fourth 
the diameter of another, it has but one-sixteenth of 
its area. Thus the area of the cross sections of 
circular pipes are to each other as the squares of 
their diameters. 

As circles and squares always bear the same rela- 
tive proportions to each other, and as either can be 
likened to the cross section of a pipe, the hegiimer can 
always find the number of times the area one pipe will 
divide with another, by making another, by making 
a square, a', Fig. 75, and calling the side of it the 
diameter of the smallest j)ipe ; then around the smaller 
square construct a larger one, the side of it being the 
diameter of the larger pipe, with the corner h form- 
ing a common corner for both squares. Thus if the 
square a' represents a 1-inch 
pipe, and you draw around it a 
square 3J inches on the side, 
and lay the larger square off 
into squares of the size of the 
smaller one, as shown, the num- 
ber of the whole squares and 
the sum of the parts of the 
square within the larger square 
is the number of times a 1-inch pipe will go into a 
3|-inch pipe. 

It will be seen there are nine whole squares, six 
half squares, and one quarter square, which equals 
12J squares ; the number of times a 1-inch pipe will 
go into a 3f-inch pipe. 



r T— j 

cef. ' I I 

J--j._...L..j 

' ' I 



L_J 



I""tg. 75- 



168 STEAM BEATING FOR BUILDINGS. 

To prove the above according to tlie rule — ^** Pipes 
are to each other as the squares of their diameters, " 
si|uare the smaller pipe for a divisor, and the larger 
pipe for a dividend, and the quotient will be the 
number of times. 

Example : 

1X1 = 1. 3.5 X 

3.5 
175 
105 

l.)13.25(12.25— Ans. 
Ex. — To find how many times a J-iuch pipe will go 
into a 2-incli pipe. 



.75 X 

.75 


2.x 
2. 


375 
525 


.5625)4.0000(7.11— Ans= 
3.9875j 


.5625 


6250 
5625 




6250 
5625 



625 + 

The following table has been calculated for the 
use of the steam and gas-fitter, and shows how many 
times the area of one pipe will go into another. 

In practice, however, with pipes of constant lengths, 
more branches may be taken from a pipe than are 
here shown. 

A large pipe, having less frictional surface for its 
area than a smaller, will do more work — pass more 
water or steam — other things, such as length, pres= 
sure, etc., being the same for both pipes. 



dTJSAM PIPE, SIZE, AREA, EXPAJ^StOIT, ETC. 169 



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170 



STEAM HBATINO FOR BUILDINGS. 



When lengths and pressures are equal, the discharge 
or quantities of steam, water or air that pipes will 
pass will be the ratio of the square root of the fifth 
power of their diameters. For instance, in the fol- 
lowing table the upper lines represents diameters of 
pipe, and the second line quantities of steam : 



Diameter 


1" 


2" 


3" 


A" 


5' 


6" . 


7" 


8" 


Quantity 


1 


5.65 


15.6 


32.0 


55.9 


88.3 


129.6 


181.0 


Diameter 


9' 
248. 


10" 


11" 


12" 










Quantity 


316. 


401. 


498. 





Conversely to the above, the diaineters of pipes, for 
equal lengths and pressures, will be directly as the fifth 
root of the square of their diameters. 

To use the table of the relative areas of pipe. — Find 
the size of the smaller pipe, in the left-hand column, 
and follow it to the right, until it is under the size of 
the larger pipe, or vice versa; the number thus found 
is the times the small pipe will go into the large one. 
The accompanying diagram, Fig. 76, also illus- 
trates graphically and almost at a glance, the relative 
proportions of pipes, from one inch to twelve inches 
in diameter ; the column of figures being the diame- 
ters of the pipes in inches. 

The 1-inch pipe is represented by one triangle ; the 
triangle immediately opposite the figure. 

The 2-inch pipe is represented by four triangles ; 
the three immediately opposite the figure and the one 
above it. 

The 3-inch pipe is represented by nine triangles ; 
the five immediately opposite, and all above it ; and 
so on to the end. 



STEAM PIPE, SIZE, AREA, EXPANSION, ETC. 171 

The sum of the triangles immediately opposite the 
size of a pipe, and all the triangles above it, gives the 
square of the diameter in inches. 

The number of triangles immediately opposite the 
size of a pipe, gives the increase in units of size (the 
unit being the area of a 1-inch pipe") over the pipe 
next smaller than it ; and the number of triangles, 

A DIAGRAM OF RELATIVE AREAS OF PIPES, FROM I TO -12 INCHES, 
SHOWING THE INCREASED AREA FOR EACH INCH OF INCREASE OF 
DIAMETER. 



1 

2 


\ 


\ 




3 


\ 


\ 


\ 




^ 


\ 


\ 


\ 


\ 




J 


\ 


N 


\ 


\ 


\ 




6 


\ 


\ 


\ 


\ 


i\ 


\ 




r 


\ 


\ 


\ 


\ 


\ 


\ 


\ 




8 


\ 


\ 


\ 


N 


\ 


\ 


\ 


\ 




9 


\ 


\ 


\ 


\ 


\ 


N 


\ 


\ 


\ 




40 


\ 


N 


\ 


\ 


\ 


\ 


\ 




\ 


^ 




Ji 


\ 


\ 


\ 


\ 


\ 


\ 


\ 




\ 




\ 


iZ 


\ 


\ 


\ 


\ 


\ 


\ 


\ 


\ 


\ 


\ 


\l\ 



Fig. 76. 



opposite the size of a pipe, with all above it, as far 
as the size of any other pipe, gives the increase 
on units for the difference between the two sizes. 

It will also be seen that the increase of the area of 
pipes, for each inch of increase of diameter, is an 
arithmetical progression, whose common difference is 
two, the first term being one. 



172 STEAM HEATING FOR BUILDINGS. 

These simple metliods may be tiresome to the ad-= 
vanced student, but the writer knows from contact 
with the workingman for 25 years that a subject can- 
not be made too simple. 

EXPANSION OF PIPES. 

In running pipe for any purpose, special atten- 
tion must be given to its expansion or contraction, 
for nearly all leaks which occur after work is com- 
pleted and tight, if not due to defective material, are 
caused by expansion or contraction, which has not 
been provided for. 

When a main pipe is run close to a wall, and 
branches taken through holes in the wall, the holes 
being just sufficient for the branches to pass, the latter 
break off, when heated. If main pipes run some dis- 
tance from the wall, the branches being unconfined 
near the main, even though confined near their farther 
ends, the spring of the pipe, especially if it is of small 
diameter, will admit of the expansion or contraction 
of the main in the direction of its own length without 
rupture. But the branches should not be confined in 
the direction of their length, or they will shove the 
main out of line, and should another branch start, 
directly opposite to a branch so confined, the Tee will 
either be pushed out of position or cross broken. 

Main pipes, to look well, must be straight and 
should be hung so they will expand in the direction 
of their length, avoiding all the side motion possible 
and throwing the expansion of the branches in the 
direction of their own lengths. 

Long mains should never be run very close to a wall 
up which risers go ; for the risers admit of very little . 



STEAM PIPE, SIZE, AREA, EXPANSION, ETC. 173 

lateral movement, aud all the linear expansion of the 
main will be thrown on the riser-connection in the 
form of torsion. 

When a main is turned with its branch Tees looking 
up, a nipple and elbow can be screwed into the Tee, 
so as to get any desired angle in running to the wall 
or elsewhere. This nipple and elbow, with the pipe 
from the elbow, will admit of more torsion than a 
straight pipe, and in extreme cases the threads of the 
nipple will turn a little and prevent anything from 
breaking. 

Special attention should be given to pipes laid be- 
tween floors, or when they have to cut into floor joists 
or beams. They must not be confined at their ends, 
and their branches for 3 or 4 feet from where they 
leave a Tee, and should have room enough to allow for 
the greatest possible difference of length or change of 
position in the rising line. 

It is common for steam-fitters to run their re- 
turn pipes around cellars and basements before the 
concreting is done, and to allow them to be buried 
and cemented into this mass, which becomes as one 
stone, and for a time (when they do not give out upon 
the first turning on of steam,) must actually over- 
come the elasticity of the iron. But the pipe more fre- 
quently breaks or leaks, either by shoving through 
the threads of the fittings, or else pulling them apart, 
or the branches break off by having a large pipe, 
which may not be confined at one end, forced past 
them. 

There is another reason why pipes shuld not 
be buried in floors, — namely, lime with moisture de- 
stroys them rapidly. Work so hid from observation is 



174 STEAM HEATING FOR BUILDINGS. 

the first to give out. If connections around boilers, 
pumps and the like, were kept above the floor, thej 
would probably outlast the boiler. 

When hot water or steam has to be carried 
under ground, it must be conveyed in wrought-iron 
pipe, with screwed joints, or cast-iron pipe, with 
flanged joints. Hub and spigot pipes with leaded 
joints are not suitable, for it is impossible to keep 
them tight when subjected to much difference of tem- 
perature, as the lead expands in a different ratio from 
the iron, and takes a permanent set with compara- 
tively little pressure. 

Cast-iron gas or water pipes, put down in the 
streets, with leaded joints, it is said, will compensate 
in the joints by slipping ; the difference on a twelve- 
foot length being about the -^ of an inch for a differ- 
ence in temperature of 20 degrees. 

There is another explanation of this matter, which 
is probably the true one. It is that the pipe, being 
firmly held to the ground, its whole length is actually 
compressed equally at all parts of its length, the same 
as it would if subjected to compression by weight. 
Cast-iron is sufficiently elastic for this. 

The steam-fitter should avoid using expansion 
joints (slip joints) when it is possible to compensate in 
any other way. In private houses and city buildings 
it can always be avoided by taking advantage of right 
angle turns ; but frequently in long runs of pipe, in 
narrow passages and with pipe of large diameter, they 
must be used, as spring bends cannot be used unless 
they have considerable length, and a four or five-foot 
turn, on a 6-inch pipe, if the expansion was only one 
inch or that due to about 50 feet of pipe, would be 



STEAM PIPE, SIZE, AREA, EXPANSION, ETC. 175 

very liable to make miscliief. An eight-foot turn, on 
a 2-inch pipe 100 feet long, will compensate for any 
cliiference of temperature that may take place, with 
ordinary ranges of pressure ; but on a 4-inch pipe it 
A ould in all probability break,' assuming that the long 
run of pipe is prevented from springing sidewise. 

Sometimes in running pipe through long, straight 
passages, if the passages have a width of about 6 feet, 
by frequently crossing from side to side we obtain a 
beneficial result ; especially if it is a return pipe. The 
objection to this method for a steam pipe is the great 




number of turns which would be required for a pipe 
larger than 2 inches ; but when passages make one or 
two right angle turns, nothing can be better if the pipe 
is hung and has not to pull or push its own weight 
over rough surfaces, the length of pipe each way from 
the elbow not being sensible of any considerable 
bending. 

When several boilers are connected together 
between their domes or ends, the connections should 
not be run " short across " from dome to dome. The 



176 



STEAM HEATING FOR BUILDINGS. 



pipes should be run back or forward from the domes 
3 to 6 feet, and then connected across. 

The reason of this is plain, when we consider 
that the settling of the brickwork or the expansion 
of -the pipes will suffice to throAV the weight of the 
boilers on rigid connections. For the same reasons 
pipes passing through the brickwork of boilers should 
not rest in the walls, but have large holes, covered 
with loose flanges, around the pipes. 

Figs. 77 and 78 show plans of boiler connections, 
the first when using expansion joints, and the latter 




Fig. 78. 

when the expansion is provided by spring, the latter 
being the most permanent way when properly done. 

By reference to the figures it will also be seen that 
a slip joint only provides for a linear contraction 
or expansion, or a twisting motion, and does not com- 
pensate for a difference in level. 

Fig. 78a shows a view of some high pressure boiler 



STEAM PIPE, SIZE, AREA, EXPANSION, ETC. 177 











^ '■ -44 



. %. 




Fig. 78a, 



178 



STEAM HEATING FOR BUILDINGS. 



connections in a modern power-house, where bent pipes 
are used to provide for expansion. 

Fig. 79 shows distant rigid objects connected by a 
pipe, in which the expansion is provided for by the 
use of spring bends. 

The expanding power of a 2-inch pipe, when heated 




Fig. 79. 



to the temperature of 100 pounds of steam, exerts a 
force sufficient to move 25 tons. 

Oast-iron expands one one-hundred and sixty- 
two thousandths (y^ooir ) ^^ its length for each degree 
Fahrenheit it is subjected to within ordinary limits, 
while in the solid state. Its expansion is less than 
wrought-iron. 

Wrought-iron pipe expands one one-hundred and 
fifty thousandths (-j-g-yiy-Q-Q-) of its length, for each de* 
gree Fahr. it is subjected to in any limits it can be 
used by the steam-fitter ; and the length of the jDipe 
in inches, multiplied by the number of degrees it 



STEAM PIPE, SIZE, AREA, EXPANSION, ETC. 179 

is lieated and divided bj 150,000, will give the expan- 
sion for that difference iu temperature in inches, or 
fractions of an inch. 

Example. — Find what the length of a one hundred 
feet of pipe will be, when heated to the temperature of 
100 pounds of steam, its initial temperature being zero. 

ft. in. in. temp. 

Thus, 100 X 12 = 1200 X 328° = 405600 -- 150000 = 
2.70 inches. (See table.) 



TABLE OF LINEAR EXPANSION, OF WROUGHT AND 
CAST IRON PIPES (TO WITHIN THE ^i^ OF AN INCH), 
FOR EACH 100 FEET IN LENGTH, AT TEMPERA- 
TURES AND PRESSURES MOST FREQUENTLY RE- 
QUIRED BY THE STEAM-FITTER.* 

WROUGHT IRON. 



Temperature of 


Length of 

pipe when 

fitted. 


Length of pipe when heated to 


the Air, when the 
pipe is litted. 


215° or 1 lb. 
of steam. 


265° or 25 lbs. 
of steam. 


297° or 50 lbs. 
of steam. 


3380 or 100 
lbs. of steam. 


Degrees, Fahr. 


Feet. 


Feet. Ins. 


Feet. Ins. 


Feet. Ins. 


Feet. Ins. 




33 
64. 


100 
100 
100 


100 1.73 
100 1.47 
100 1.21 


100 2.13 
100 1.78 
100 1.61 


100 2.31 
100 2.12 
100 1.86 


100 2.70 
100 2.45 
100 2.19 



CAST IRON. 




33 

64 


100 
100 
100 


100 1.59 100 1.96 
100 1.36 100 1.65 
100 1.13 100 1.43 


100 3.20 
100 1.96 
100 1.73 


100 3.50 

100 3.37 
100 3.00 



* Calculated for Regnault's temperatures and Lavoisier and Laplace's 
difference of expansion. 



Rolled wrouglit-iron expands tlie 150000tli part of its 
length to each degree Fahrenheit it is warmed, and 



180 STEAM HEATING FOR BUILDINGS. 

soft irons and forgings expand slightly more, whereas 
steel as a general thing expands somewhat less. For 
all practical purposes, such as the architect or the 
steam-fitter have to deal with in heating, steel and 
iron may be assumed to expand substantially the 
same, varying slightly with the conditions of its hard- 
ness, etc. 



CHAPTEPv XV, 

SIZE OF MAIN PIPES FOR LOW PRESSURE STEAM HEATING 
APPARATUS, AND WHY SUCH SIZES ARE NECESSARY. 

No gravity heating apparatus is perfect unless 
it heats thoroughly at all pressures ; unless the water 
of condensation runs back and into the boiler at all 
pressures ; unless it is noiseless under all ordinary 
conditions, so that the duty of the person in charge 
is simply to take care of the fires and see there is 
always sufficient Avater in the boilers. 

The fitter in all probability knows that a gravity 
apparatus requires larger pipes than any other system, 
and thus he can take it for granted the size of piping 
sufficient for a gravity apparatus will be enough for 
any other description of work. 

As this pipe is principally devoted to the heating of 
buildings and blocks, which have their own boilers, 
situated either in the buildings or near to them, the 
rule mentioned hereafter is intended for determining 
the size of main pipes for gravity apparatus for all 
ranges of pressure, or where pressure is required 
throughout an apparatus that is nearly an initial pres- 
sure — that is, a pressure the same as within the boiler 

181 



182 STEAM HEATING FOR BUILDINGS. 

to within, say, -J- pound, or at most 1 pound, at tlie 
remotest part of the apparatus, — as witli an automatic 
direct return steam-trap job or an exhaust steam job. 
With high pressure steam, which is allowed to 
expand through a building and eventually escape 
through atmospheric traps or tanks, a very much 
smaller piping will do ; but the waste of heat is some- 
times very great with traps which discharge into an 
open tank or to atmosphere. The difference in favor 
of a gravity apparatus, or an apparatus working 
properly, with direct return traps or pump-governing 
system, can always be estimated at 15 per cent, over 
apparatus which permits the water to escape and thus 
loses it, with the heat it contains ; and when traps are 
neglected (which is the rule) it may reach 30 per cent, 
of all the heat. 

This is not an assertion in the interest of direct 
return, or one which cannot be verified, as the follow- 
Lng will show. 

When water is returned to the boiler at a tempera- 
ture of 180° (the ordinary temperature of water from 
gravity apparatus), it requires 1,000 heat units to make 
one pound of it a pound of steam, and in condensation 
to water again, and returning it to the boiler at 180°, 
it loses just 1,000 heat units ; which have all been 
utilized within the building. Thus every unit of heat, 
added to the water, has been realized, and it repre- 
sents the maximum economy possible in steam heating ; 
the power required to put the water back being at a 
minimum — i. e., gravit3^ In the case of an apparatus 
that wastes its return water, and has to pump water 
from the waterworks at a temperature of 40°, it has to 
add to every pound of water converted to steam, 1,140 



SIZE OF MAIN PIPES,, ETC. 183 

units, and gets only 1,000 from it, when tlie water is 
cooled to 180° (a very low temperature, by the way, 
for ordinary traps to expel water at). Thus, for every 
1,140 units added to the water, 140 are lost, or over 
12i per cent. When the pressure in the radiator is 
40 pounds and the water j)asses the trap at a tern- 
perature corresponding to that pressure (285° Fahr.), 
more heat is allowed to waste, as there are 1,140 units 
required to raise fresh water at a temperature of 40° 
to steam at 40 pounds, and only 902, utilized in cooling 
to 285°, the temperature of water at 40 pounds, which 
leaves 245 units unaccounted for, or a loss of more 
than 21J per cent. ; and this does not take into con- 
sideration the heat lost in pumping water into the 
boiler. 

The power necessary to pump water into a 
boiler is a little over J of 1 per cent, of all the power 
obtained from the steam, and for common pumps it 
should be placed at not less than 1 per cent, of all the 
steam. In fewer and plainer words, i per cent, of the 
steam furnished by the boiler is a fair allowance to be 
chargeable to putting the water into the boiler again^ 
when it has to be done by a steam j)ump. 

If the water from traps, discharging at 40 
pounds pressure, is saved in one tank, and pumped into 
the boiler again, then the condensed water, after being 
received into the tank, will have a temj^erature of 
about 200°. But it will be said the water escaping 
from a trap at 40 pounds pressure had a temperature 
of 285°, hence the water will be received at that tem- 
perature if the tank is kept under j)re.ssure ; and this 
is true of the modern pump and governor method of 
returning condensed steam. But where it is neces- 



184 STEAM HEATING FOR BUILDINQS. 

sary to have a tank open to the atmosphere (with 
either an overflow pipe or a vapor pipe) to receive the 
water, and as water at a pressure of the atmosphere 
cannot have a temperature above 212°, the difference 
will escape in vapor, or low pressure steam, through 
the vapor pipe ; and if we have a tight tank without 
traps, we must have as large pipes, or nearly as large 
pipes, to get water to gravitate to the tank as are 
required for boiler gravitation ; so that when the 
difference in a cellar or basement will permit, it is 
better to put the water of condensation directly into 
the boiler than to trap or pump it. But to return. 
The temperature of the water in the open tank we will 
take at 200, and to raise a pound of it to steam will 
require 979 units, and only 894 units of it will be 
realized in cooling, if it passes the trap at a tempera- 
ture corresponding by getting into a condition fit to 
remain in the tank — this is over 8j- per cent., to which 
add 1 per cent, for pumping the water back, and the 
sum will equal 9|- per cent ; but should the water be 
lost each time and fresh cold water be supplied, it will 
equal 21f per cent. 

Thus it will be seen, it is poor economy to use 
small pipes and resort to tanks, traps, pumps and 
other contrivances, to get water back, when the price 
of a steam pump expended on larger pipe is frequently 
sufficient to get the water back, and obtain an effect, 
which so far as the heating surface is concerned, will 
give the maximum duty, and do away with one source 
of continual expense, as well as the loss of heat occa- 
sioned by such irregular means. Twenty-five or thirty 
years ago it was excusable, in some, because it was not 
("hen generally known that water could be returned at 



SIZE OF MAm PIPES, ETC. 185 

all pressures ; but now it is unpardonable, wlien the 
circumstances of the case, position of buikling, etc., 
will admit of doing better. Furthermore, it should 
be the duty of the architect to provide, if possible, for 
direct return in the general planning of buildings, at 
least for direct heating, when there is little or no ex- 
haust steam to be taken care of, such as in public 
institutions and private residences, particularly the 
latter. Since the use of exhaust steam has become 
general in the big office buildings of the country it 
has become necessary to pump and return condensed 
water by mechanical means. It was the custom some 
years ago to take steam from the boilers to run the ele- 
vator pumps and other engines of the building, and 
waste the exhaust steam and take live steam for the 
heating apparatus from the same boiler, though by 
another pipe. This, however, is now all changed in 
this class of buildings. New York City buildings, and 
big buildings throughout the country to-day, use much 
more steam for their elevator service and electric light 
service than can be condensed in the heating ap- 
paratus, and no designer or engineer with any regard 
for his reputation will now waste the exhaust steam> 
but will turn it into the heating apparatus and con. 
dense it as far as it will go, often having to waste a 
considerable quantity of it through the exhaust pipe, 
not being able to condense it all ; though sometimes 
having to add a little live steam to make up a de- 
ficiency when the exhaust is not sufficient. Appa- 
ratus of this kind, of course, cannot be on the grav- 
ity system, though usually the size of the pipes given 
for gravity work seem to suit this class of work better 
than any other, for the reason that the pressures of 



186 STEAM HEATING FOE BUILDINGS, 

steam are so small that it will require pipes equally 
as large as for gravity work, though perhaps not al- 
ways run in the same manner. 

The Exhaust System of Steam Heating will be 
treated of more fully in a later chapter. 

The conditions first cited, however, are often found 
in factories and country workshops where the heating 
pipe is taken from the boiler that makes steam for the 
engine and carried to heat the factory or office. The 
condensed water and discharge from the traps is often 
found running into the sewers or drains of the build- 
ing, or into a creek if one is near by ; but the waste 
from the loss of the water, etc., does not stop here. 
It will be found occasionally there are no traps on 
the pipe, the whole thing being controlled by a valve, 
though more frequently it will be found that the traps 
are inoperative and allowed to waste the best way 
they can, in which case there is often more steam 
going to waste than is required for warming that part 
of the building. We are, however, going away from 
our subject, and the reference above given was here 
introduced as a most conclusive argument for prop- 
erly arranging the size of the pipes and the system of 
heating to be used at the outset. 

There is no very definite rule among those 
who do steam-heating, or there certainly was not 
before the first editions of this book were in print, by 
which they may determine the correct size of pipes ; 
hence much confusion and many failures, to the gen- 
eral injury of the trade, though of recent years a great 
improvement has been made in this respect. Those 
who make a specialty of heating soon find they must 
use large pipes, and they generally adopt some arbi- 



SIZE OF MAIN PIPES, ETC. 187 

fcrary unit, sucli as to allow tlie size of a f-inch pipe 
to each radiator ; a lialf a square inch in the cross sec- 
tion of the horizontal main to each 100 square feet of 
heating surface or to each radiator ; and the area of a 
one-incli pipe to each 100 square feet of heating surface. 
The latter I early adopted as a rough rule for my work- 
men, the only one that in my experience was ample. 

This rule also compares very nearly with deduc- 
tions made from the steam pipes of certain buildings 
throughout the country which are considered repre- 
tative i^ieces of w^ork, and have proved themselves 
ample wdien the greatest cold prevailed. 

Thus, the area of a one-inch steam pipe, 0.7854 
of a square inch, may be taken as the unit ; and it 
serves very well, as by simply squaring the diameter of 
a pi23e in inches, you have the number of 1-inch pipes, 
or units, or hundreds of square feet, of pipe or plate 
surface, the main pipe will surely supply steam if 
the pipes are not of too great a length. Thus a 3-inch 
pipe will supply steam for 900 square feet of heating 
surface, w^hen subjected to the greatest condensation 
possible within buildings, and still not raise the water 
line in the pipes to any appreciable extent. 

It happens that the area of a one-inch pipe (0.7854 
of a square inch ) makes a very satisfactory unit. 
The diameter of a steam pipe always increases di- 
rectly as the square root of the heating surface, 
and according to the arbitrarj^ unit here adopted, the 
diameter of the pipe in inches, will be exactly one-tenth of 
the square root of the heating surface, in feet. Thus, 
when you find your heating surface, extract its square 
root, in feet, and call one-tenth of it the diameter 
of the main, in inches. 



188 



STEAM HEATING FOR BUILDINGS. 



This is on the assumption that the mains in- 
crease in length in a certain proportion to their diam- 
eters. For instance, assuming the 2-inch pipe to be 
not over 50 feet in length, the 2|- about 75 feet long, 
3-inch 100 feet, a 4-inch pipe about 150 feet, a 5-inch 
pipe about 200 feet, aud each successive size about 
100 feet longer than the one that preceded it. 



HEAT 
SURF 
IN SQ 

1000. 

c 

2000. 
3300. 
4000. 
5000. 
6000. 

7000. 
8000. 

9000. 

D 
10000. 


ING 
ACE 
R.FT. 
100. 

A 
200. 

800. 

400. 

500. 

600. 

700. 

800. 

900. 

B 

1000. 


DIAMETER OF PIPE IN INCHES. 

'/ 'f // // // // // // // 

123456789 lb 


A 


\ 




1 


^X 


\ 














\ 


\ 






\ 


\ 


^ 














\ 






GRAI 


'HIC IL 


.USTRi* 


rioN 
















( 


)FTHE 


sizeVo 


• STEA 


VI PIPE 










i 
1 

1 




FOF 


GRAVI 


rV HE* 


TING A 


PPARA1 


L 














\ 










\ 


\ 












\ 
\ 






\ 






\ 












\ 






\ 








\ 










B 


\ 






\ 






\ 



Fig, 8o 

These are about the conditions found in long, low 
buildings, such as insane asylums, hospitals, depots, 
etc., and the accompanying diagram. Fig. 80, may be 
used without much error for such buildings. It illus- 
trates the subject at a glance, and gives the size of main 
pipes for surfaces, from 100 to 10,000 square feet. 



SIZE OF MAIN PIPES, ETC. 189 

The ordinates of the curve, A B, gives diameters 
corresponding to the square feet of heating surface in 
the column marked A B. 

The ordinates of the curve C B bear the same rela. 
tion to the column C B 2j^ the curve A B bears to the 
column A B, and shows the size of pipe for heating 
surfaces from 1,000 to 10,000 square feet. 

It will be seen that 1,000 at the head of the column 
AB corresponds to 1,000 at the bottom of the column 
CD, the ordinates of both curves agree near the 
3-inch pipe. 

Example. — Required the size pipe, for 600 square 
feet of heating surface. Find 600 in the column, and 
follow the horizontal line to where it crosses the curve 
A B ; then follow the nearest perpendicular line to 
the nearest size of standard pipe above the line, in case 
it should not come exactly on a standard size ; in this 
case it is a little below 2^-inch pipe, which size should 
be taken. 

Pipe of less than IJ inches diameter should not be 
used horizontally in a main, unless for a single radia- 
tor connection. 

All this, of course, is an empirical rule founded on 
good practice. The rule, however, is closely correct 
for practical conditions, and for all sizes of pipes up 
to about six inches in diameter is not likely to give 
results much greater than claimed for it. In practice 
in small mains, say smaller than three inches or when 
they appear to be slightly longer than usual, I gener- 
ally take the next size larger pipe than will be given 
by this rule, and I look on the rule as furnishing sizes 
that are just ample for gravity work without being 
in the least unnecessarily large. 



190 STEAM HEATING FOR BUILDINGS. 

This rule may be used to determine the size of 
the steam pipe in radiator connections by increasing 
the 'pipes one size, to give them a practical magnitude, 
to overcome loss by short turns, etc. Main pipes 
should not decrease in size, according to the area of 
their branches, but should be proportioned at their 
various stages by the same rule as for determining the 
size of the main the first time. The same is true of 
the large branches. Find surface they have to supply 
steam for, and proportion them as you would a main 
close to the boiler : figuring their own surface as radi- 
ating surface unless they are to be covered. When 
the mains and distributing pipes are to be covered 
with some good nonconducting material, their surface 
need not be figured as against their size, but when 
they are excessively long, or exposed in cold places, 
their surface should be considered. 

Of course it is not necessary to use main pipes of 
as great a diameter as given above, if the mains and 
coils are very much above the boiler ; but for cellars 
or basements 10 feet, or under, in height, it will not 
be found too large or wasteful. Discretion also can be 
used in the use of this rule, Avhen pipes run 4 inches 
or over, as 2,000 to 2,500 feet of direct heating surface 
may be taken from a 4-inch pipe under favorable cir- 
cumstances, provided its branches follow the rule 
closely. A 6-inch pipe will be ample for 5,000 feet of 
surface under good conditions, high basements, and 
10-inch for 15,000, if not too long, or rather, if short, 
and such as are found in city buildings that are high 
but on a small ground area. 

For pipes of equal short lengths the increase of 
diameters would be in the ratios of the fifth root of 



SIZE OF MAIN PIPES, ETC. 191 

the square of the radiating surface, as mentioned be- 
fore, which would call for about a 2J^-inch pipe for 
1,000 feet of surface, a 4-inch pipe for 3,000 square 
feet, a 5-inch pipe for 5,500 square feet, and a 6-iuch 
pipe for 8,700 square feet ; and this will be ample foi 
short lengths of straight pipe without elbows, but not 
for the ordinary ramification of pipes of a building. 
The line EE shows diameters for constant lengths. 

Between the lines E E and CD of the diagram 
are to be found the true conditions for high buildings 
with short mains, such as are to be found in New 
York and other large cities. 

If the line EE is used, add at least one inch to the 
diameter of the pipes to overcome the resistance caused 
by the short turns of valves and elbows. Then, as the 
buildings decrease in height and increase in horizon- 
tal area, go nearer to the line CD. 

These sizes will do for either exhaust steam work 
or gravity work under fair conditions. 



CHAPTER XYL 

STEAM. 

Tempeeatures of steam, according to the ^dif- 
ferent formulas, all agree at the atmospheric pres- 
sure, but as the pressures become high, they vary 
slightly : Regnault and Bankine are nearly alike, 
while the experiments of the Franklin Institute are 
about five degrees higher for 75 pounds apparent 
pressure. 

The technical terms, used about steam by 
writers, and the expressions in vogue amongst steam- 
fitters, want some explanation to make them clear, as 
many of them are synonymous, and the fitter does 
Qot always know what is meant. 

Temperature. — A condition of a body which in all 
cases determines its readiness to part with heat to 
surrounding bodies or to receive it from them. It is 

192 



STEAM. * 198 

usually expressed iu Englisli and American books in 
degrees of Fahrenheit's scale. The heat of steam as 
distinguished from the heat in steam. 

Pressure — Is the force of steam, usually expressed 
in pounds per square inch, and called " elastic force,'* 
" expansive force," " tension," and " elasticity," etc.^ 
are synonyms. 

Density. — The weight of a cubic foot of steam com- 
pared to a cubic foot of water. Syn. — The weight of 
water necessary to form the steam. 

Maximum density of steam. — The density of steam 
when it is neither superheated nor laden with parti- 
cles of water mechanically. Syns. — Steam at its max- 
imum density is called dry saturated steam or dry 
steam. 

Superheated steam. — Steam expanded by heat, or 
under an increased pressure, due to an increase of 
heat, without the addition of water. The steam is, of 
course, dry beyond the point of maximum density. 

Wet steam. — That containing water carried by force 
of ebullition, and held in the steam by the rapidity 
of evolution, when the steam space of a boiler is not 
large enough. 

Foaming. — A condition differing from wet or satu- 
rated steam, by having an excess of some foreign 
substance in the water, causing it to foam and seem 
lathery, and which appears to give the water in the 
boiler a bulk above what would be due to the pres- 
sure, by retarding the proper separation of the steam 
and raising the whole mass of water into a froth. 
Syns. — Priming ; drawing water. 



194 STEAM HEATING FOR BUILDINQS. 

This condition differs from " priming." Priming is 
generally a meclianical effect, while foaming is the 
results of foreign substances in the water. Foaming 
and priming are often confounded. To prove whether 
the boiler is foaming or priming it is only necessary 
to shut the main valve on the boiler tightly for a 
moment, when, if the boiler is foaming, there will be 
no change of level in the water glass, whereas if the 
boiler is priming through a mechanical effect, the 
water will at once seek its proper level and remain 
constant until the valve is again opened. Foaming 
may cause priming by sending water out of the boiler 
through the steam pipes ; in other words, priming 
may take place with dirty water when it will not take 
place with clean water. Priming and foaming may 
occur together. 

Volume. — The space occupied by a given quantity 
of water, should the water be converted into steam. 
The relative volume of steam decreases as the pressure 
increases. Syns. — Relative volume ; bulk for bulk. 

Specific gravity of steam. — The weight of its volume 
compared to the same bulk of water, air, or any other 
substance it is contrasted with. Syn. — Density. 

S'pecfic heat of dry-saturated steam. — The heat of a 
given iveight of steam compared to a given weight of 
water or any other substance it is contrasted with. 
The heat necessary to raise the temperature of a 
pound of steam one degree while it remains continu- 
ally at its maximum density. 

The annexed table gives the apparent pressure 
of steam from atmosphere to 100 pounds in pounds 
per square inch, absolute pressures in inches of mer 



STEAM. 



195 



cury, and temperatures in degrees Fahrenheit (to with- 
in one-half degree), according to Kegnault, the volume 
beino- calculated. 



TABLE NO. 5. 

ELASTIC FORCE, TEMPERATURE AND VOLUME OF STEAM. 



ELASTIC FORCE. 


Temperature 
of Steam 


1 

RELATIVE VOLUME 


Average Rise of 






Temperature 


Apparent 
Pressure of 
Steam in lbs. 
per Square 


Absolute 

Pressure in 

Inches of Mer- 


corresponding 
to its Press- 
ure. 


1 
Vol. of Steam 
compared to Vol. 
of Water. 


for one lb. 
Pressure for 
each 10 lbs. 


Inch. 


cury. 











30.0 


212.0 


1710.0 


1 


1 


32.03 


215.5 


1612.0 




2 


34.07 


219.0 


1523.0 




3 


36.11 


222.0 


1442.0 




4 


38.15 


225.0 


1372.0 




5 


40.18 


227.5 


1312.0 


-2.8 


6 


42.22 


230.0 


1248 




■7 


44.27 


232.5 


1194.0 




8 


46.30 


235.0 


1168.0 




9 


48.33 


237.5 


1103.0 




10 


50.37 


240.0 


1061.0 




11 




242.0 






13 





244.0 


.... 




13 


.... 


246 







14 


. 


248.0 






15 


m.k 


250.0 


895.0 


-1.76 


16 





252.0 


.... 


17 


.... 


253.5 






18 


. . . . 


254.5 






19 




256.0 






20 


70.75 


257.5 


'7i8.0 




21 


.... 


259.0 


.... 




22 





260.5 






23 


.... 


262.0 






24 


.... 


263.5 


'766.0 




25 


80^91 


265.0 


684.0 


-1 5 


26 


... 


266.5 


.... 




27 





268.0 


.... 




28 . 


.... 


269.5 






29 




271.0 






30 


9i!i2 


272.5 


'614.0 





196 



STEAM HEATING FOR BUILDmOS, 



TABLE No. 5-^Conimued. 



ELASTIC rORCE. 


Temperature 
of Steam 


RELATIVE VOLUME 


A.verage Rise of 








Temperature 


Aijpai'ent 

Pressure of 

Steam in lbs. 

per Square 


AbsoMe 

Pressure in 

Inches of Mer- 


corresponding 
to its Press- 
ure. 


Vol. of Steam 

compared to Vol. 

of Water. 


for one lb. 
Pressure for 
each 10 lbs. 


Inch. 


cury. 








31 





274.0 






32 






275.5 


.... 




33 






277.0 


.... 




34 






278.5 






35 


loi 


!31 


279.5 


*558. 


1.3 


36 






280.0 


.... 




37 






282.0 






38 






283.0 


.... 




39 




. 


284.5 







40 


lii 


5 


285.5 


'516 




41 






286.5 


.... 




42 




. 


288.0 


.... 




43 
44 


•• 


• 


289.0 
290.0 





-1.15 


45 


121 


7 


291.0 


'476. 




50 


131 


88 


297.0 


435. 




55 




. 


302.0 


. 


■1.0 


60 


152 


25 


307.0 


'390. 


65 




, 


311.0 




•0.8 


70 


172 


43 


315.0 


*343. 


75 




. 


320.0 




■ 0.8 


80 


193 





323.0 


305. 


85 






327.0 


.... 


■0.7 


90 


213* 


38 


331.0 


'283. 


95 






334.0 




■0.65 


100 


233" 


76 


337.5 


'260. 



IS 



When the j^i'sssure iii inches of mercury 
not given, multiply the apparent pressure in pounds 
per square inch by 2.0376, and the answer will be the 
inches of mercury above atmospliere ; or that which an 
old fashioned mercury column would show. 

Example.— 10 pounds X 2.0376 = 20.376 inches of 
mercury. 

If the absolute pressure is required, add 30 to the 
above. ( 20.37 + 30 = 50.37. See table,) 



STEAM. 197 

When the volume of steam is not given, add 459 to 
the temperature of the steam ; multiply the product 
by 76.5, and divide by the absolute pressure in inches 
of mercury ; the answer is the volume^ or number of 
cubic feet a cubic foot of water will occupy when 
made into steam at the pressure required. 

Example. — Required the volume for 10 pounds pres- 
sure, temperature 240° Fahr.— 240 + 459 = 699 X 76.5 
= 53473.50 -^ 50.37 = 1061.6 (see table). 

To find what a cubic foot of steam will weigh at 
different pressures, divide 1000 by the volume^ corre- 
sponding to the required pressure, and the answer 
will be the weight in ounces. 

Example. — What will a cubic foot of steam at maxi- 
mum density weigh, at 40 j^ounds per square inch? — 
Volume 1000 -^ 510 = 1.96 oz. 

To find the number of cubic feet of steam a pound 
of water will make at the different pressures. — Divide 
the weight of a cubic foot in ounces (as above) into 
16, and the answer will be the volume in cubic feet to 
the pound. 

Example. — How many cubic feet of steam, at twenty 
pounds pressure will one pound of water make?— 
Volume 1000^718=1.39; 16-1.39=11.5 cubic feet to 
the pound of water. ( See Diagram of dry saturated 
steam.) 

To find the weight of steam necessary to raise a 
given quantity of water a certain number of degrees. 
Subtract the lowest temperature of the water from 
that to which it is to be heated for a dividend, — 
subtract the highest temperature of the water, from 
1147 for a divisor, and the quotient from these will 



198 



STEAM HEATING FOR BUILDINGS. 







rn^ 




tJs^^ 




j^ 




-K i/ 








o 




'" ^^ 




%> 












9 




(is*:}' ^iR'^LQ 


A. XI IT ATFrk 






^rk'^ q 


-TIF- AM 


CC 65 _ _ a 


jIy^^' 


111 / R A MIT- N- 


E^-F^RMUlLA — 




I ^'^^ 




^ fio 4'_L : 




cow -^ 




o - -A-^V- 




^ <^ tr 




f : ^ :iij 




•" K- '^'^ "T* 




< 5o ^^ 








i^ 1-rf^^^ y 




> 1^ ^cc 




O 'Ul V T 








5? o° -'^ 




< :\Uv :y^ 




T ITC - 




S ^K VI 




^ *^ \ .1 




z 1 _^_^^g_ 








111 r^^ -D' 








^40- tf ~ "v ~ 




< " 1 ° ,.:S 




3 J J&>^ CC 




g i«g^ -a 








"^ 1 J^ 




cc t ° :4r^, 




m \^ 'd-Vit 




n \^J: \^ 




qn J, 




,« '"^ 




S2 ^ ^ 




°^. V o^'" 




_j V <^ - 




' ' 




Z 25 V 




■^ i ° ' 




LU \ vJ^ '' 




a "Y*^ 












CO 




P^ 1 vc^d-^ 




UJ ^ cK' 




oc ,r "^t^ 




Q. 15 \ 








5 v<; 


^ ^' 


- di^l 




in 5LZ 




]f^ ^ 










^ yi° A 




S-Mi^ 


^ 


%p 












^ 






10 


30 "^v^r 30" 



CUBIC FEET TO THE POUND 

Fig. 8 1. 



STEAM. 199 

be the weight of the steam compared to the weight of 
water. 

Example. — Find the weight of steam necessary to 
raise water from 75° to 190°. Thus 190° - 75° = 115, 
tor a dividend 1147. — 190 = 957 for a divisor, 115 ^ 
957 = .12 or -jLSq- the weight of the water. 

To find the weight of Avater, a given weight of steam 
will heat. — Proceed as above, only transpose the di 
visor and dividend. 

Example.— 957 -f- 115 = 8.32 times the weight of 
the steam. 

The accompanying diagram, Eig. 81, of Ran- 
kine's formula has been modified to commence at the 
atmospheric pressure — 15.7 of the absolute scale, 
being one pound here, and shows at a glance the 
cubic feet of steam to the pound weight of water at 
the different pressures, as well as the temperatures 
corresponding to the pressure. 



CHAPTEE XVIl. 

HEAT OF STEAM. 

The unit of heat is the amount required to raise the 
temperature of one pound of water one degree Fahr- 
enheit, and is the standard measure of values used in 
all calculations pertaining to heat. 

The equivalent in work of the unit of heat is the 
raising of approximately 772 pounds avoirdupois one 
foot high, and is called the mechanical equivalent of heat. 
The expenditure of one heat unit will raise the tem- 
perature of 52.5 cubic feet of dry air from 32° to 33° 
Fahrenheit. In very accurate calculations the moist- 
ure in the air should also be considered, but as it is a 
variable quantity it cannot be considered here. In 
approximate calculations, when estimating the heat 
necessary for the air of a building, it may be assumed 
that 50 cubic feet of air at the average outside winter 
temperature of air, warmed 1 degree Fahr., is the 
equivalent of the heat unit, and it can be taken as a 
constant. 

Sensible and latent heat.— Steam has a temperature 
corresponding to its pressure, as given in the table, 
and this apparent temperature is known as the sensible 
heat of steam. But it is found that steam contains 
more heat thaa a thermometer will show, heat that 

200 



HEAT OF STEAM. 201 

can be made manifest in the warming of air, water, 
etc., and by warming a very much larger quantity 
than would appear by a comparison of the tempera- 
ture of the steam with the ordinary temperatures of 
water. This extra heat, which is not sensible to the 
thermometer, is called the latent heat of steam. 

When a solid becomes a liquid, or a liquid becomes 
a vapor, heat is absorbed by the body in greater quan- 
tities than is necessary to raise it to the temperature 
at which the change of state occurs. This latent heat 
does work in the destruction of the force of cohesion 
and other occult changes which take place, and must 
be aborbed from some substance. In the case of water 
and steam in a boiler, it comes from the fuel during 
combustion, and when a pool of water is vaporized in 
the street the heat comes from the sun directly, or 
from the earth, air, etc., indirectly. When steam or 
vapor is condensed, this same quantity of heat that 
Avas received, no matter where, is again given off to 
any substance within its influence, air, water, etc., 
colder than itself ; and it is this property, to convey 
more heat within ordinary controllable temperatures 
than any other substance which makes water and its 
vapor so valuable.* 

It takes as much heat to melt a pound of snow from 
a temperature of 32°, to water at 32°, as would warm 
a pound of water from 70° to 212°. This heat is 
absorbed by the water in changing from a solid to a 
liquid, and must be given off again before the water 
can be frozen. 

* Water has the greatest specific heat of any known substance, with 
two unimportant exceptions j one of them being the principal component 
of water. 



■ STEAM HEATING FOR BUILDINGS. 




Fig. 8io. 



With water from the tem- 
perature of ice (about 32° 
Fahr.) to 212° under the pres- 
sure of the atmosphere, there 
is no heat made latent in con= 
finement, each pound of water 
receiving only 180 heat units ; 
but in the conversion of one 
pound of water at 212°, to 
steam at 212°, it receives 966 
more units of heat ; enough to 
warm h^ pounds of water from 
32° to 212°, or to cool 9 pounds 
of iron from redness to zero. 
This heat is the latent heat, 
and the real thermal value of 
the steam. 

The sum of the sensible and 
latent heat of steam is nearly 
the same for all pressures. 
At atmospheric pressure the 
sensible heat is 212°, and the 
latent 966°.6, giving 1,178°.6 
as the total heat. At 100 
pounds the sensible heat is 
337°.5, and the latent 874°.8, 
giving 1212.3 as the total heat, 
the difference being 33.7, but 
this difference is not manifest 
in the heating of water when 
the steam is not allowed to 
expand to atmospheric pres- 
sure in cooling, as it expands 
itself in force, which would be 



HEAT OF STEAM. 203 

manifest in an engine. Steam allowed to expand to 
its full volume against the pressure of the atmo- 
sphere exerts nearly the same force as if expanded 
against the piston of an engine. Actually, the extra 
heat is carried out of the boiler, at high pressures, 
beiug another form of heat made latent, the extra uuits 
remaining in the steam in the form of stored energy 
until it is expanded. 

The assertion, therefore, that the total heat of steam 
is the same for all pressures is nearly correct in making 
calculations on warming, as it is presumed the steam 
is expanded to atmosphere in use ; but when high 
pressure steam is condensed to water under its own 
pressure, then the total heat of the steam can not be 
considered, as the latent heat for the given pressures 
onl}^, is available. The total heat of steam, however, 
increases, according to the experiments of Eegnault, 
as the pressure advances, and the annexed diagram, 
Pig. 81a, has been constructed from the tables of Reg- 
nault, to show the way in which this increase occurs. 

It also shows the number of ujiits of latent and sen 
sible heat of steam compared with each other, the 
ordinates of the curves AB showing the sensible 
heat, from one pound pressure to 200, counting from 
the line marked zero, or counting from any other imag- 
inary line, as 32° (ice), or from the line JS'i^, which 
may be taken as the temperature of return water. 
The difference between ordinates of the curve A B 
and the curve G D, gives the latent heat of steam for 
the different pressures noted. The difference between 
the ordinates of the curve G D and the constant line 
1146.6, shows the increase of the sum of the heat 
above the constant 1146.6. 



204 ISTEAM HEATING FOR BITILDINGS. 

A pound of water converted to vapor in the open 
air, or a pound of water vaporized from clothing in a 
drying-room, requires very nearly the same heat as 
would be required to evaporate one pound of water 
to steam in a boiler, and for all practical calculations 
it may be taken as the same. Thus, the weight of 
steam necessary to dry clothing or to evaporate water 
in any kind of cooking apparatus, etc., can never be 
less than the weight of the water driven off in steam 
or vapor ; and of necessity it will be greater, to sup- 
ply the loss by radiation, or in warming the fresh air 
of a drying room (which must be changed as often as 
it becomes saturated), and for other reasons. 

Equivalents of heat. — The heat necessary to warm 
a pound of water at mean temperature (39° Fahr.) one 
degree {the heat unit), will warm very nearly four (3.94) 
pounds of air, one degree ; 2^10- pounds of vapor of 
water, one degree ; 9 pounds of iron, one degree ; and 
very nearly 2 pounds of ice, one degree."^ 

The heat necessary to convert one pound of water 
from the temperature of feed water, or return water, 
at 178°, to steam at one pound pressure (or to any 
pressure, not noting the slight increase for high 
pressures), is 1,000 heat units, and will heat 52,500 
cubic feet of dry air one degree, above 32° Fahr., or 
5,250 cubic feet of air 10 degrees ; or 525 cubic feet 
of air 100 degrees, making no allowance for the expan- 
sion of the air, which will increase the bulk \ for a 
difference of 100 degrees ; in other words, the 525 
cubic feet will be increased to 630 when heated 100 
degrees, and the 5,250 will be increased to 5,360 or 

* It mustnot be confounded with melting the ice, but refers to chang- 
ing the temperature of ice below 32 degrees. 



BEAT OF STEAM. 205 

3^ of its bulk for a rise of temperature of 10 
degrees. 

The heat necessary to warm one cubic foot of water, 
from the temperature of the return water to steam, is 
capable of warming 45,572 cubic feet of dry air from 
zero to 72°, but if the air absorbs only 5 grains of 
vapor of water for each cubic foot— as from clothes in 
drying room, or wet walls of a building — it will be 
equivalent to the fall of the temperature of the air to 
34.5. If the moisture is already in the air, and has 
only to be warmed (superheated), it will not be equal 
to the cooling of it more than one and a half degree. 

One grain of water vaporized is equivalent to cooling 
from 7.5 to 8.6 cubic feet of air one degree, according 
to the initial temperature of the moisture, and is a 
constant ; but 1,000 grains of vapor already in the air, 
warmed any number of degrees, cools only SJ- to 4 
cubic feet of the air the same number of degrees. 

When water is evaporated at the expense of the heat 
of the air, it makes a large factor, which cannot be 
overlooked ; but vapor already in the air, when warmed 
along with the air, forms a small factor and is not ot 
much practical consequence. 

The above facts explain why a new damp building 
often proves difficult to warm for the first few months, 
while later on there is often an over-abundance of heat 
from the same apparatus. 



CHAPTER XVIII. 

AIR. 

Air is a mixture whose parts are not cliemicaily 
combined, consisting of about 77 per cent, of nitroaen 
and 23 per cent, of oxygen, by weight, when considered 
pure, i. e., when it is in the condition best suited to 
support animal life. It also contains from about ^ ^ ^ ^ ^ 
to 3-qVo ^f i*^ volume of carbonic acid gas, according to 
circumstances and location, and some watery vapor, 
and is capable of absorbing any other gas or vapor, 
to a certain extent, distributing them throughout the 
whole atmosphere, by what is called the lata of gaseous 
diffusion, a property which gases have of mixing and 
diluting, which prevents gases of the most opposite 
specific gravities from stratifying for any considerable 
time. Prof. Youmans says this eifect will be produced 
even through a membrane of india-rubber ; carbonic 
gas rising and mixing with hydrogen, though twenty 
times heavier. Thus, exhaled air, and air contami- 
nated in any other way, is perpetually made respirable 
by diffusion. 

This property is of the utmost importance to air, 
for if its elements were to become separated, or an 
added noxious gas to remain separated from the mass, 
deadly gases would be the result in all unventilated 

206 



Ain. 207 

places in a very short time. It frequently happens in 
mines and wells, Avhere the entrance is small, and 
there are not sufficient disturbing influences, that in- 
jurious gases become abundant, the diffusion being 
too slow. 

In confinement, air may have its oxygen increased 
or diminished ; an increase of 2 or 3 j)er cent, causing 
fever, and a diminution of 3 per cent, causing death, 
if the carbonic acid gas from the lungs is exhaled into 
such air and the air inhaled afterward. 

The amount oi fresh air necessary for respiration for 
an adult is often stated to be about 300 cubic feet in 
24 hours. This general statement, however, is mis- 
leading, and the idea that is intended to be conveyed 
is, that an average individual requires the oxygen of 
about 300 cubic feet of air in each 24 hours to support 
life. Air cannot be breathed in such a manner that 
all its oxygen will be extracted. 

Air in rooms is likely to be breathed again, in a more 
or less degree, and as it is vitiated by moisture from 
the skin and lungs, and by other means well known 
to people of ordinary intelligence, 300 cubic feet per 
hour is far too little to provide in ordinary ventilat- 
ing ; and then not with the expectation of keeping the 
air fairly pure, but rather in a state which will not be 
injurious, even if it receives no other contamination 
than that from the body in health. 

Hospitals should be supplied with ventilating appa- 
ratus capable of supplying at least 3,000 cubic feet of 
air per hour to each patient, with means to double oj 
quadruple the quantity by forcing it (as with a fan). 
in times of contagious disease, or in very oppressive 
weather. 



208 STEAM HEATING FOR BTTILDINOS. 

School and class-rooms should have at least from 
1,500 cubic feet of fresh air per hour per child, for 
large children or the higher classes, to 1,000 cubic feet 
for small children, ranging between as the classes 
advance. This is considered a fair allowance in view 
of the practical difficulty of admitting so much air in 
the aggregate without making drafts. The Massachu- 
setts school law requires " 30 cubic feet per minute 
per scholar ; " in other words, 1,800 cubic feet per 
hour per capita. A theatre, or other auditorium, 
should have at least 1,000 cubic feet of fresh air per 
hour per capita, and double that quantity is not ex- 
cessive. Chambers in dwelling-houses should have 
1,500 cubic feet per hour per sleeper. 

Even with these amounts of air moved, a room may 
be poorly ventilated and poorly warmed also, if proper 
mixing of the air is not produced within the room. 
This is accomplished by the positions of registers, 
both inlets and outlets, but it principally depends on 
the outlets. 

The size of a room has no particular bearing on the 
amount of air to be admitted, if it is to be occupied 
continuously. Four workers or four sleepers will be 
about as well oif in this respect in a room of 1,000 
cubic feet as they would be in one of 4,000 cubic feet, 
provided the fresh air is admitted to both alike. If 
there is little or no ventilation, then the large room is 
the better, as the air already in it may be assumed to 
be pure, and it will take four times as long to vitiate 
it to a given standard as it will the small one. 

An ordinary kerosene lamp requires the oxygen of 
about 40 cubic feet of air in an hour, and possibly viti- 
ates the air as much as two persons in the same time. 



AIR. 209 

Air, assumed as unity, is taken as tlie standard of 
weight of gases, when its temperature is 60° Falir., 
and the barometer 80 inches. Air for the same weight, 
at a temperature of 32°, occupies 775 times the space 
water does, a cubic foot weighing 565 troj grains. 
At the temperature of 32°, 12|- cubic feet of air weighs 
(very nearly) one pound avoirdupoisj which increases 
to IS^^, l4yV/and 15, for 60, 70 and 100 degrees re- 
spectively.* 

The expansion of air is nearly uniform at all tem- 
peratures, expanding about ^J-g- of its bulk at 32°, and 
for each increase of one degree in temperature Kegnault 
puts it a little less, while Dr. Dalton puts it as high as 
-^^, and other authorities have put it at -^J-g- ; any of 
these ratios are near enough for small differences of 
temperature. The following table will show the in- 
crease or decrease in volume of one thousand cubic 
feet of air at a temperature of 32°, when the expansion 

is TIT- 
TABLE NO. 6. 

Zero. 
Temperature... 20°—, 10°—, 0, 10" + , 20° + , 

Volume 895, 914, 935, 953, 975, 

Temperature... 32° + , 40° + , 50°+, 60° + . 

Volume 1000, 1017, 1036, 1057, 

Temperature... 70° + , 80°+, 90° + , 100° + , 

Volume 1077.5, 1098, 1128, 1139. 

To compute the volume for other temperatures, its 
volume at 32° being unity, use the following — 

Eule. — Divide the difference between 32° and the 
required temperature by 490 ; to the answer add one 

* One pound of air at 32 degrees Fahr., under tlie pressure of the atmo- 
sphere (29.9 mches of mercury) will occupy a space of I2.387 cubic feet, 
and its specific heat is 0.2379, water being unity at the same temperature. 



210 STEAM HEATING FOR BUILDINGS. 

(whole number), if the required temperature is above 
32°, but if it is below, subtract it from one and multi- 
ply the volume of air at 32, by it. 

Example. — Find the volume a thousand cubic feet 
of air at 32° will have at 212°. Thus, 212^ - 32° = 
180°-h 490 = 0.367+1.0 = 1.367x1000 + 1367.0 cubic 
feet. 

To find what a given volume of air at 70° will be at 
40°. — Multipl}^ the volume by the number correspond- 
ing to 40°, and divide by the number corresponding 
to 70°. 

To find what a given volume at 40° will be at 70°. — 
Multiply by the number corresponding to 70°, and 
divide by the number corresponding to 40°. 

Example. — Bequired, what a volume of 3147.0 cubic 
feet of air at 100° will be at 50°.— Thus, 3417x1036 
= 3539988.0 -~ 1139.0 = 3108.0 cubic feet. 

The following table is copied from a text-book, and 
given as Dr. Dalton's No. 7, though it does not agree ac- 
curately with that which is given as his difference of ex- 
pansion ; it agrees very nearly with other tables which 
are given as his. It shows the increase of bulk from 
75° to 680° when the volume at 32° is 1,000. 



AIB. 



211 



TABLE NO. 7. 



Fahr. 


Bulk. 


Fahr. 


Bulk. 


Temp 


75 


...1099 


Temp 


97 


....1146 




76 Summer heat . . 


...1101 




98... 


....1148 




77 


...1104 




99 


....1150 




78 


...1106 




100 


....1152 




79 


...1108 




110... 


....1173 




80 


. ..1110 




120 

130 


1194 




81 


...1112 


....1215 




82 


...1114 




140 


...1233 




83 


...1116 




150 


...1255 




84 


...1118 




160 


....1275 




85 


...1121 




170 


....1295 




86 


...1123 




180 


...1315 




87 


...1125 




190 


...1334 




08 


...1128 




200 


....1364 




89 


...1130 




210 


....1372 




90 


...1132 




212 Water boils. . . 


....1375 




91 


...1134 




302 


....1558 




92 


...1136 




392 


...1739 




93 


...1138 




482 


....1919 




»4 


...1140 




572 


....2098 




95 


...1142 




680 


....2313 




96 


...1144 









Air is capable of holding a certain quantity of 
vapor of water, or any other condensable vapor, in 
solution, so to speak, the proportions depending on 
the temperature of the air. The warmer the air is, 
the larger quantity it will hold, and as it becomes 
cool again the vapor is deposited or forms clouds or 
fog, which condense on anything colder than the air, 
leaving the air when warmed capable of taking up 
more moisture, to be again deposited in dew or rain. 
It is this property of air which gives it its drying 
qualities. 

The atmosphere is seldom laden with moisture to 
its utmost, and is usually capable of taking up more 
moisture ; the difference between the total amount of 



212 STEAM HEATING FOR BUILDINGS. 

moisture the air can hold and the actual amount in it 
is the drying power of the air. 

An absolutely dry atmosphere is hardly possible. 
The coldest air contains some moisture, but it is not 
always possible to tell how much, as air is seldom 
saturated to its maximum ; so to iind the quantity of 
water air at a certain temperature is capable of taking 
up, a quantity of the air must be cooled until the 
moisture becomes apparent — forming a dew point — 
when a knowledge of the quantity of moisture already 
in the air can be had from tables (the result of ex- 
periments of Dr. Dalton and others, who have made a 
study of the hygrometric state of the atmosphere) 
which give the greatest quantity of vapor the air is 
capable of containing, for the different temperatures. 
Thus, if air is cooled from 70 to 50, and shows conden- 
sation at the latter point, all the moisture the air is 
capable of taking up for 70 is the difference between 
the quantities of vapor at those temperatures in the 
table. 

The object in introducing this subject and in giving 
the following table of the quantities of vapor air is 
capable of taking up, is to show the great economy 
there is in time and the saving in heat by having the 
highest possible heat in a drying room that will not 
injure the goods or materials to be dried. 



DIAGRAM SHOWING GRAINS OF VAPOR AIR IS CAPABLE 
OF TAKING UP, PER CUBIC FOOT, AT DIFFERENT 
TEMPERATURES. 









































260' 








































250' 








-^ 
































240° 














^ 


























230° 
















\ 


\ 






















220° 




















\ 




















212° 






























































\ 


\ 
















2i0" 
200° 


























\ 














190° 




























\ 


V 










180° 






























\ 










170° 
































\ 








160° 


































\ 






150° 


































\ 






140° 




































\ 




130° 




































\ 




120° 




































\ 




110° 








































100° 
















— 
























90° 








































80° 








































70° 






































\ 


60° 






































' 


50° 








































40° 








































30° 








































20° 








































10° 








































0° 



570 540 510 480 450 420 



330 300 270 240 210 180 150 120 90 60 30 GR. 

Diagram Fig. 8 1 3. To face page 2\2,. 



AIR. 



213 



TABLE NO. 8. 

A TABLE OF THE QUANTITY OF VAPOR OF WATER WHICH AIR IS 
CAPABLE OF ABSORBING TO THE POINT OP MAXIMUM SATURATION, IN grains 
PER CUBIC FOOT FOR VARIOUS TEMPERATURES. 



Degrees Pahr. 


Grains in a cubic 
foot. 


Degrees Fahr. 


Grains in a cubic 
foot. 


10 


11 


85 


12-43 


15 


1-31 


90 


14-38 


20 


1-56 


95 


16-60 


25 


1-85 


100* 


19-13 


30 


2- 19 


105 


22-0 


32 


2-35 


110 


25-5 


35 


2-50 


115 


30-0 


40 


306 


130 


42-5 


45 


3-61 


141 


58-0 


50 


4-24 


157 


85-0 


55 


4-97 


170 


112-5 


60 


5-82 


179 


138-0 


65 


6-81 


188 


166-0 


70 


7-94 


195 


194-0 


75 


9-24 


212 


265-0 


80 


10-73 







It will be seen bj a study of the table, tliat tlie 
quantity of vapor per cubic foot of air increases very 
rapidly as the temperature advances — a common dif- 
ference of about 25 degrees in the rise in temperature 
of the air, doubling the quantity of moisture it is able 
to take up. Hence, all other things being equal, an 
increase in temperature of 25 degrees in a drying-room 
will reduce the time for drying about one half, and an 
increase of 50 degrees will reduce the time to one- 
fourth, and so on in that geometrical ratio. 

The diagram is made to correspond to the table 

* Up to ICO degrees the table has been copied from the Encyclopaedia 
Britannica, where the full table, advancing by single degrees, can be 
found. Beyond loo degrees the table has been calculated (by the author) 
from the elastic force of vapors according to Regnault, and is approxi 
"•lately correct. 



214 STEAM HEATING FOR BUILDINGS. 

No. 8, and the ordinates of the curve show grains of 
vapor each cubic foot of air is capable of taking up. 
It also shows that the quantity of moisture air is cap- 
able of taking up, agrees with the elastic force of the 
vapor of water. In other words, the maximum amount 
of vapor of water a cubic foot of air is capable of takng 
up, is the amount necessary to fill a cubic foot of 
space with steam at a pressure that would give a cor- 
responding temperature. 

The saving in heat by using a high temperature is 
not so apparent, as it takes just so much heat to 
vaporize a certain quantity of water, and the quantity 
of heat is a constant. But there is a saving in not 
having to heat the air and the moisture it contains 
from its initial temperature, so many times to carry 
off the given amount of moisture ; in other words, the 
amount of heat necessary to evaporate the moisture 
will be the same for all temperatures, but the quantity 
of heat lost in the application is less. 

A house 40 X 40 feet is warmed and ventilated on 
two stories. Each story is 11 feet in the clear, mak- 
ing 33,600 cubic feet, and it is desirable to change the 
air in the house once in each hour. In order to know 
its cost, a business man would proceed to figure in 
the following way : The steam-heater has told him 
the apparatus would convert 10 pounds of the return 
water to steam, at an expenditure of one pound of 
coal, consequently the next thing to know is, what is 
the equivalent of one pound of coal in the warming of 
air. Now it is admitted that' a cubic foot of water, 
losing one degree of its heat, will warm 3,000 cubic 
feet of air one degree, and that one pound of it will 
warm 50 cubic feet of air one degree ; but in convert- 



AIE. 215 

iug the pound of water to steam, 1,000 heat units are 
absorbed, which, of course, will warm 50 cubic feet of 
air 1,000 degrees, or 500 cubic feet 100 degrees, or 
5,000 cubic feet 10 degrees.* Thus the fact is estab- 
lished, tliat a pound of steam returned to Avater will 
warm 5,000 cubic feet of air 10 degrees. For the sake 
of safety, and to get the price as Mgh as the poorest 
practice would make it, he takes only one-half the 
theoretical quantity of the coal and figures it at 7 
pounds of water to the pound of coal. Thus we have 
5000 X 7 = 35,000 cubic feet of air, which can be 
w^armed 10 degrees by one pound of coal. But it ap- 
pears that 10 pounds of coal have been burned per 
hour, a quantity sufficient to warm 35,000 cubic feet 
of air 100 degrees, while the air in the room has been 
only 70°. Whence, then, is this apparent discrepancy ? 
Assume air outside to be 20° Fahr., and as it passes 
the heat registers it has a temperature of 120°, having 
been warmed just 100 degrees in passing through the 
indirect radiator ; but an examination of the air, as it 
goes out at the ventilating register, shows its temper- 
ature to be 70°, which would suggest 50 degrees of 
the heat had been utilized in the rooms in maintain- 
ing the temperature, and the other 50 had escaped 
through the ventilator, and been lost as heat ; but it 
has produced ventilation, and the movement of the air. 



* The quantity of air, water or steam will warm, is figured according 
to the specific heat of each for the same weight. Approximately, water 
requires 4.2 times as much heat to warm a given weight of it any number 
of degrees as the same weight of air ; but as air occupies 775 times the 
space water does, for the same weight, it will have to be multiplied by 
this factor (relative volumes), and by the heat. — Thus, i X 775 X 4.2 
= 3255. As air contains a little moisture, which mxist be warmed also, 
the odd 255 may be dropped, and is usually figured at 3,000. 



216 STEAM HEATING FOR BUILDmOS. 

Now, the ventilating flues aggregate 2 square feet of 
cross section, and the air, as it escapes, has a velocity 
of 5 feet per second in the middle of the flues, and 
which, if it were not for the friction of the sides, would 
pass 36,000 cubic feet in an hour. Making some al- 
lowance for friction, we will say 35,000 cubic feet of 
air passes in an hour, exactly the cubic contents of 
the part of the house, ventilated ; taking one-half of 
all the heat with it, or what represents 5 pounds of 
the coal burned in the hour. 

Thus the ventilation of a good home can be fairly 
done for IJ cents per hour, when coal costs 5 dollars 
per ton ; less than 3J cents per 100,000 cubic feet of 
air moved under conditions which all preponderate 
against the price, the difference of temperature be- 
tween the inside and outside being 50°, which is a 
high average. 

There seems to be a simple relation between the 
amount of heat necessary to maintain the temperature 
in a room and the amount passed off in ventilation, no 
matter at what temperature the air passes the register 
entering the room, in indirect heating. 

For instance, let air enter at 20°, and instead of 
raising its temperature to 120° it is raised to 95° as 
it passes into the room. The difference between the 
temperature of the room, 70°, and 95° and 120°, is as 1 
and 2. Thus, if the windows, etc., cool a certain quan- 
tity of the air, from 120° to 70°, they will cool twice 
that quantity from 95° to 70° to maintain the same 
heat, and twice the quantity of air will have to pass 
out through the ventilator at half the greater differ- 
ence to make room for the fresh supply necessary to 
keep up the heat. So the temperature at which air 



ATE. 217 

passes through the heat registers only affects the 
quantity of air moved, and not the total heat. 

This also points to another result — namely, the less 
the difference between the temperature at which the 
air leaves the heat register and the temperature at 
which the room is to be maintained (so long as it 
proves sufficient), the more air there must be passed 
in a given time to keep up the required warmth, which 
will of necessity make the air purer. 

A private house kept properly warm by indirect 
radiation alone, with air entering the rooms at about 
100° Fahr., cannot be other than sufficiently ventilated 
for the number of persons who would ordinarily oc- 
cupy it. The lower the temperature at which the air 
will pass the registers and maintain the heat of the 
room or building, the more assurance the occupant 
may have of the efficiency of the apparatus as a ven- 
lator« 



CHAPTER XIX. 

HIGH PRESSURE STEAM USED EXPANSIVELY IN PIPES 
FOR POWER AND HEATING. 

It lias been customary, when speaking of steam- 
heating apparatus, to divide them into two kinds — 
called respectively high and low pressure ; but these 
terms cannot nowb© accepted in their literal meaning, 
any more than high and low pressure would express 
the difference between non-condensing and condens- 
ing engines. 

When steam has been let into pipes at any pres- 
sure and run arbitrarily to suit the convenience of 
some one Avho wants steam at a distance, under the 
supposition that steam will pass to any place where 
pipes can be put (as it will when certain conditions 
are complied with), such piping used to be called a 
high pressure system, which is now synonomous with 
" expansive system," and implies steam used expan- 
sively for heating. 

The conditions alluded to are : The steam must 
be allowed to expand, to blow through in fact, if the 
pipes are not run on some system that provides for 
taking away the water at every low point in the 
piping; and the quantity of steam used in a given 

218 



BIGH PRmsURE STEAM. 219 

time must be sufficient to carry along the water of 
condensation which forms in the pipe during trans- 
mission. 

Scattered buildings, heated from one source, must 
be heated expansively, if they have no basements, and 
are on different levels, and the condensed water must 
be taken care of by steam traps. 

The system is usually attented with considerable 
waste of heat from imperfect steam-traps, etc., and 
requires the constant vigilance of the engineer. It 
should not be used in single buildings when it is 
possible to install a gravity apparatus or a pump 
governor system. 

Within the last 10 or 15 years this system of 
expanding steam through pipes has been used in the 
heating of towns and cities ; but it is only the old 
system on a larger and grander scale, where instead 
of heating three or four buildings from one source 
hundreds are supplied with steam for engines and for 
heating purposes. 

The magnitude of the apparatus generally prevents 
any attempt to take back the condensed water, which 
of necessity is wasted after it is cooled to its utmost 
practical limit ; and as the water becomes the prop- 
erty of the consumer it can be used in the house for 
culinary purposes, and in the laundry, if the rust 
from wrought iron pipe, carried along with the water, 
will not discolor clothes. 

In New York and in other cities a return pipe was 
used when the system was first introduced. It is now 
abandoned, as it became defective rapidly, although 
the steam pipe is still in use and in fairly good order. 
For some reason, not satisfactorily explained, the re- 



220 STEAM HEATING FOR BXJILBINQS, 

turn pipe is eaten or destroyed very much faster than 
the steam pipe. In the supply pipe the steam is, of 
course, nearly pure, while the water in the return 
pipe has the fatty acids, etc., from the engines in all 
cases where the exhaust steam from the engines is 
carried into the heating apparatus and thence to the 
main return pipe in the ground. This is presumably 
one reason for the deterioration of the return pipes in 
city systems faster than the steam pipes. 

With steam used entirely for heating purposes, I 
am of the opinion the return pipe lasts nearly as 
long as the steam pipe, when protected on the outside 
in a proper manner. Dampness and moisture is a 
factor in destroying any pipe from the outside, and 
those that are subject to heat and cold alternatively 
with moisture will rust out quickly. 

In 1882 the New York Steam Company commenced 
the most stupendous undertaking ever contemplated 
for the i3roduction of steam, and carried it to a 
partial success in point of magnitude, and to a prac- 
tical success from the engineer's standpoint. 

The scheme embraced the establishment of some 
twelve or fourteen stations (named after the letters of 
the alphabet), to be distributed through the city, and 
to be erected as the requirements of the districts seem 
to demand and justify. 

Two of these stations were built in New York City, 
one being " Station B," which is situated on the west 
side of Greenwich street, between Courtland and Dey 
streets, and is built on a ground space of about 75 
feet by 150 feet. The other is uptown, in a residential 
portion of the city, and of much smaller capacity. 

Fig. 82 is the ground plan of the Greenwich street 



HIGH PRESSURE STEAM. 221 

station and sliows the irregular shape of the building, 
with the foundations for chimneys and piers. Fig. 
83 is the first story plan, and may be properly 
said to represent each of the four floors on which the 
boilers are set. Fig. 84 is a section about on 
the line A' B\ and shows a view through one chimney 
on its greatest axis, with the approximate position and 
setting of the boilers and the floor trussing and col- 
umns. Fig. 85 is a section on the line C D\ show- 
ing a chimney on its shortest axis ; and Fig. 86 is 
the facade, whose principal feature is the immense 
opening in the brickwork (/), which extends from al 
most the roof to the water table, and which is fitted 
with portable or easily moved sections, to allow for 
the ingress and egress of heavy machinery. 

The positions marked B^ between the columns, are 
where the boilers are placed, with their fronts and 
fire doors facing on the fire room D, It is intended 
to have 4,000 Jiorse-poiuer to a floor, each position be- 
tween columns containing 250 horse-power, making 
for the four floors of boilers an aggregate of 16,000 
horse-power. 

The boilers used are the Babcock and Wilcox water- 
tube type, and there may be said to be two boilers in 
a nest (between each set of pillars,) or to the same fire 
grate, the horizontal steam and water drums of each 
being connected by a large cross pipe, virtually mak- 
ing them one boiler. 

The boilers are suspended and do not rest on the 
brickwork or fire front, and are set substantially as 
shown, the fire being under the front or high end of 
the tubes and the products of combustion passing be- 
tween the tubes into a chamber under the steam and 



222 



STEAM HEATING FOR BUILDINGS. 



water drum, then down between the tubes to the 
back of the bridge-wall, thence up again and to the 
chimney. 

The circulation of the water within these boilers is 
up through the tubes, where it enters the drum and 
flows backward and down again to the tubes, givingc 
it is claimed, extraordinary good results as a steam 
maker, and preventing, to a great extent, the formation 



^^^^^ 




^^^^^^ 




Fig. 83. Fig. 82. 

of deposits upon the inside surfaces and allowing all 
loose substances to settle into the mud-drum. 

One of the objects for selecting these boilers for the 
peculiar situations they here occupy, aside from 
their high efficiency and the small cubic capacity 
they occupy for horse power, is their supposed abso- 



HIGH PRESSURE STEAM. 



223 



lute safety from any kind of burst or 'explosion that 
would materially injure the building or other boilers 
above or below them. 

I will now follow the water from the time it enters 





SECTION ON LINE A-B' 

Fig. 84. 



Fig. 86 



the boilers, through its changes and stages, to the 
consumer, and back again to the boilers in the station, 
and describe details as they suggest themselves in 
that order. 

There are no feed water heaters used, the return 
water, with the steam necessary to force it around its 
circuit, presumably being sufficient to heat the water 



224 



STEAM HEATING FOR BUILDINGS. 



necessary to be supplied to make up for the loss 
caused by steam supplied to engines. 

The water enters the boilers before described, where 
it is converted into steam, thence it is passed through 
an 8-inch pipe to about an 18-inch main, see dotted 
lines q r, which runs above and in front of the boilers, 




HIGH PRESSURE STEAM. 225 

through the fire room D, and connects with the verti- 
cal cylinder h which conyeys the steam to the base- 
ment, preparatory to distributing it to the street. The 
main connections from the drrans of the boilers to the 
pipe r are partly comj)osed of copper, and are supplied 
with bends of long radius, to give elasticity to the 
branch and an easy flow to the steam. Each is fitted 
with an angle stop valve of special design, the posi- 
tion of the valve being close to the main pipe r. This 
valve, an idea of which can be had from the diagram, 
Fig. 87 is to prevent the steam from the whole sys- 
tem flowing backward and escaping through one 
boiler, should any part of it give out. It is a com- 
bined stop and check valve ; the steam from the boil- 
ers as it passes into the general system having to force 
its way under the disk which it raises, but which 
would be instantly thrown down, checking a back 
flow from the main if the bursting of a tube caused a 
difference of pressure between the main and one 
boiler. 

From the bottom of the cylinder h, which is 3' &' in 
diameter and into which the main horizontal pipe 
from each floor connects, steam is distributed from 
the main in the street by large branches which lead 
off in different directions, the pipes which now lead to 
the street passing through the arched opening in the 
wall a, Fig. 86. These pipes are supplied with stop 
valves near the cylinder, and are for the purpose of 
shutting off one street section or sub- division without 
affecting the others. 

The largest pipes laid in the street are 15 inches in 
diameter and run down to about 8 inches. They 
are wrought-iron lap welded tubes, in lengths of about 



226 8TEAM HEATING FOR BUILDINOS. 

20 feet, with flanges on their ends and bolted together. 
The flanges are what is commonly known as " flange 
unions " and are faced true and brought together on 
a concentrically corrugated copper gasket, nothing 
but lead paint being used to form the joint. 

The pipes are not screwed into the flanges in the 
ordinary way, but are inserted and expanded in the 
same manner as a boiler tube, a groove being made 
on the bore of the flange, into which the metal of the 
pipe is pressed by a Dudgeon expander. 

From the area wall the system consists essentially 




of two pipes, a larger one for conveying the steam to 
the consumer, and a smaller one for returning the 
condensed water to the station. The subdivisions of 
the system which radiate from the station ramify in 
many directions, pipes now being laid in Broadway 
from Warren street to Bowling Green; from Broad 
way down Wall street to Pearl ; also down Pine and 
Fulton to Nassau, and Liberty street and Maiden Lane 



HIOR PRESSURE STEAM, 



227 



to "William street ; also a line in the neighborhood of 
Ann and Beekman street. On the other side of Broad- 
waj^ pipes are laid through portions of Greenwich and 
in Liberty, Cortlandt, Falton, Vesey, Barclay, Park 
Place and Warren streets, from Broadway to Green- 
wich street. 

These pipes are laid in a brick conduit, where they 
are of large diameter, and the spaces filled with ** min- 
eral wool "2. e., blast furnace slag blown to a fine floss 
by the action of steam while hot. some of the small 
pipes are covered by a wooden log bored to receive 
them and prepared to prevent rotting. 



imj 





Fig. 88. 

The pipes are placed at nearly uniform distance 
below the surface, and little attention given to 
inclination or pitch, simply following the grade of 
the ground, though, avoiding a sudden dip when 
possible. 

Bends of small magnitude, sufficient to follow the 
contour of the ground or slight deflections from a 
right-angle at street corners, made necessary by the 
irregular shaped crossings, are provided for by what 
may be called a "ball and socket " joint. It is some- 
what like a flange-union, having a convex extension on 
one face, with a corresponding concave on the other, 



228 



STEAM HEATING FOR BUILDING 8. 



the faces being segments of a true circle. When 
put together with one of the copper gaskets before 
mentioned, this makes a steam-tight joint. 

The water of condensation which forms within the 
steam pipes when everything is in full operation, is 
said to be comparatively small, but small as it may be, 
it is necessary to prevent its accumulation and not 
carry it long distances by forcing it ahead of the 
steam. At distances of about 75 feet, there is a special 
contrivance shown in Figures 88 and 89, which is va- 
riously called, "Expansion Joint," "Service Box," 




Fig. 89. 

" Junction " and " Compensator," and which, in fact, 
does more than its name implies. Its prime object is 
a compensator for the expansion and contraction of 
the iron pipes, and it also makes a suitable fitting from 
which to take the house services, but in addition it is 
the means of freeing the mains from water. The pipes 
a a are the main flow pipes. The joint itself {B) is 
anchored and firmly fastened, and the pipes which 
approach and leave it are also fastened in the middle 
of their lengths between it and the joints on each side 
of it. If now the pipe is warmed, c and c being fixed 



mGH PRE88UUB STEAM. 



229 



points, the movement and thrust of the pipes a a, must 
be toward h, which is also a fixed point, but as the 
pipes a a do not connect directly with the end of 6, but 
pass inside andconnect with the copper diaphragm (e e) 
the latter yields and bends inward, allowing the whole 
to adjust itself to the increased length. The expan- 
sion joints are numerous enough to prevent any con- 
siderable strain on the copper of the diaphragm, the 
intention being not to strain the metal beyond its 
limit of elasticity, the maximum movement when the 
joints are placed about 75 feet asunder being about 




one inch. The copper diaphragms, which are con- 
centrically corrugated, are reinforced on their outer 
sides by radial plates which fit closely at their ad- 
joining edges, each forming a sector of a hollow circle, 
and having a rib or strengthening piece on the oppo- 
site side from the pressure. They move with the 
copper and are supported at their extremities in such 
a manner as to compensate for and accommodate them- 
selves to the change in length ; in fact, they are the 
real diaphragm of the apparatus, the purpose of the 



230 STEAM HEATING FOR BUILDINGS. 

copper being merely to cover the joints between their 
edges and so render the whole steam tight.* 

Condensation which forms Avithin the pipes between 
any two " compensators " falls into the lower side o 
the annular chamber and is carried into the service- 
pipe {S), if the latter is in use, and if not in use is 
carried to the first that is in use after filling the in- 
tervening ones to the level of the bottom of the flow 

pipe. 

The water which is thus carried out of the main 
through the first services which are in use, is not car- 
ried into an engine, if one is used, nor into the heat- 
ing apparatus of the house, but returned again into 
the return water through a steam trap ; this we will 
try to explain with the help of Fig. 90. Within the 
area-wall is placed a steam trap, a modification of 
Avhat is known as the ''Nason " principle, because the 
late Joseph Nason imjDroved it and made a specialty 
of it, although I believe it was invented by Profes- 
sor Mapes. This trap takes the water which is car- 
ried in through the house-service and falls from the 
point c, through the pipe a, and discharges it into the 
return pipe, through the pipe 5, then dry steam passes 
through the pipe d, to the house. 

Trap No. 2 is to return the water which is condensed 
within the house, and will drain j^ipes either above 
or below the level of the mains in the street. 

This type of trap, is the only one, I believe, which 
can be applied to the system and take the water from 

* Steam-fitters who are acquainted with the Handren & Robins' regu- 
lator, made by the Walworth Manufacturing Co., should readily under- 
stand this principle, as it is there used to support the copper diaphragm 
which operates the valve. 



HIGH PRESSURE STEAM. 231 

the cellar floor or from g, sub-cellar. It is explained 
in the chapter on traps, and is called the " pot-trap." 

The initial pressure of steam from the street is ad- 
mitted as. far as the " house valve," beyond which is 
placed the ''regulating valve." The object of the 
latter is to cause a reduced pressure withiu the build- 
ing. The valve used is the Curtis Kegulating Valve, 
which can be adjusted to keep a nearly regular re- 
duced pressure — say ten pounds on the house side, 
while there are 50 or 60 in the street, fluctuations in 
street not affecting the house pressure. 

After the water is thrown by the intermittent action 
of the traps into the main return in the street, it flows 
back to the station and is received into a large tank, 
thence to be pumped into the boilers again. The 
position of the tank is in the ground under the side- 
walk, as at T, Fig. 82, and a large duplex pump (P) 
is set close to it. This pump is kept running con- 
stantly, forcing the water through a system of feed 
pipes which lead to all the boilers. There is a con- 
trivance which may be called an overflow or relief 
valve, arranged on the discharge pipe of the pump and 
loaded to a pressure of about 90 pounds, which allows 
the water from the pump to return to the tank, or a 
part of it to so return, should it not be all required at 
the boilers at any particular time. Each boiler is fed 
separately and independently, the feed valve being 
within the control of the fireman. 

The fuel for the use of the boilers is elevated to the 
upper story and fed through chutes to each boiler. 
The boilers are fired by hand in the ordinary manner. 

The ashes are carried away by a system of chutes 
running from the ash-pit to the basement. These 



232 STEAM HEATING FOR BUILDISGS. 

chutes are fiirnislied with a valve within the ash-pit 
aiid are within the control of the fireman. They are 
kept closed except to drop the ashes, otherwise the 
draft of the chimneys would pull on them, or should 
the forced draft be on, to prevent the air of the fan 
from escaping through them. 

At the point marked A, Fig. 83, at the east end of 
the southeast battery of four boilers, but on the second 
floor, is a fan blower with a capacity of 100,000 cubic 
feet of air in a minute. It is driven by an engine of 
about 20 horse-power, and supplies air to the fires in 
case of necessity. It is connected with the ash-pits by 
a suitable system of sheet-iron ducts and takes its air 
supply directly from the surrounding air of the floor 
but should the supply be tardy the window a can be 
opened. 

The elevators are situated at/ and/, at east end of 
the building, and are principally for taking up fuel to 
the fifth floor. 

Comparatively small piping can be used in an ex- 
pansion system, and when there is no provision for 
draining the condensed water from the pipes, a size 
barely sufiicient to carry the required steam along is 
preferable ; as in that case, the draft will carry the 
water out of the pipes ; whereas, if the pipes were 
larger, the draft of the steam would be slow enough 
to cause the pipes to fill until the contracted passage 
increased the velocity of the steam to such a degree 
that it would force itself through in irregular pulsa- 
tions and cause pouliding. 



CHAPTER XX. 

EXHAUST STEAM AND ITS VALUE. 

Among the many wlio own steam engines and the 
engineers who run them, there were comparatively 
few, until quite recently, who had a just appreciation 
of the thermal value of the clouds of exhaust steam 
continually blown to the winds from the apparently 
numberless exhaust pipes, which can be seen from 
the top of a high building in any of our large cities. 

When I say that three-quarters of the practical 
thermal value of every pound of coal burned in the 
boiler furnace is lost past recovery to the consumer, I 
am putting it at less than the actual loss ; and could 
this heat be converted into available motion, suitable 
for power purposes, it would be a boon indeed, and a 
fortune to the one who could do it. Perhaps there is 
a chance for the electrician to convert it into energy ; 
but as yet engineers can use it for heating jDurposes 
only, where its full value can be shown in the heating 
of water, air, or any tangible substance. 

The first purjjose for which the exhaust steam is 
generally employed is to warm the feed water, the 
object being to raise its temperature as high as pos- 
sible, before it enters the boiler, thereby to save fuel. 

233 



234 STEAM HEATING FOR BVILDINGS. 

In round numbers, tlie warming of tlie feed Avatei 
from 40° to 212° Falir. can condense but -f-^ of all the 
steam that passes through an engine ; provided, of 
course, the quantity of water fed into the boiler is 
only equal to that which is required for the engine. 
This then leaves -^j of all the steam that is used in en- 
gines either to be wasted or to be utilized in the heat- 
ing of buildings, or in drying-rooms, cooking, water 
heating, or other similar purposes. 

If anyone Avishes to look this matter up for them- 
selves or to convince another, it is only necessary to 
go to the tables and find that it requires but 172 units 
of heat to warm a pound of water from 40° to 212°, 
while a pound weight of steam at the pressure of the 
atmosphere contains latent heat equal to 967 heat 
units, leaving 795 heat units for some other purpose. 

Among the first questions which nearly always 
suggest themselves to the young engineer is (1) How 
hot can feed water be made ? (2) "What percentage of 
the coal does the heating of the feed water represent? 
(3) How much of the exhaust steam from an engine 
can be used in heating the feed water necessary to 
supply the loss caused in the boiler by supplying 
steam to the same engine ? (4) How much of it is left 
for use elsewhere, partly or wholly, to heat the build- 
ing in winter or for drying purposes ? 

The answer to the first question is : Water under 
the pressure of the atmosphere cannot be heated 
above 212° Tahr., and when the feed water passes the 
check valve at a temperature of 200° it should be con- 
sidered fairly satisfactory, although it is possible to do 
much better, 210° being nothing uncommon with some 
heaters. 



BXBATTST 8TBAM AND ITS VALUE. 235 

Where water is forced tlirougli a heater, the tem- 
perature can be raised higher than when drawn by a 
pump from the heater, as the lessening of the pressure 
also lessens tlie capacity of the water for sensible 
heat. 

Some makers of feed water heaters claim they can 
heat the water above 212", because it is under pres- 
sure, but it is evidently a mistake to attempt it, as 
both the water to be heated and the steam necessary 
to heat it, would have to have a pressure above at- 
mosphere and any attempt to keep a considerable back 
pressure in the exhaust j)ipe for the simple purpose 
only of warming the feed w ter above 212° is attended 
with a loss instead of a gain. 

The attempt to heat the feed water 5° above 212° 
by a back pressure of 2 pounds, the mean pressure in 
the cylinder being 50, pounds, is attended by a loss in 
energy exceeding by more than five times the gain to 
the feed water. 

The above, it must be remembered, applies only to 
the attempt to warm feed water above 212° Fahr. It 
can be made as hot as 210° Fahr. by the exhaust steam 
as it passes comparatively unobstructed through a good 
heater on its way to the outside air. On the other 
hand, the "no back pressure theory" must not be 
maintained when the exhaust steam can be all used, 
or even when a large percentage can be used, in 
warming the building. There the total gain is so 
very great when compared with the loss of energy in 
the engine that no engineer of experience will now 
conscientiously oppose it, and when an agent for an 
electric light engine or pump objects to 2 pounds 
back pressure on his engine on the ground that it was 



236 STEAM HEATING FOR BUILDmOS, 

not designed for back j)i'essure, reject tlie engine and 
look for one in wliicli a reasonable back pressure 
above atmosphere is not objectionable. 

The answer to the second question is : "When the 
feed water is raised from mean temperature, 39° or 40°, 
to 212° by the use of the exhaust steam at atmos- 
pheric pressure, it is equivalent to very nearly two- 
thirteenths of the weight of the fuel necessary to con- 
vert water at mean temperature to steam at any vres- 
sure, and 15 to 18 per cent, of the coal is the greatest 
possible saving that can be made for this, the great- 
est ordinary difference of temperature. 

To find the saving of other differences of tempera- 
ature in the feed water, divide the difference between 
the temperature of the cold water as it enters the 
heater and that at which it enters the boiler into 
1,146, less the difference between the cold water 
and 32, and the product is the fraction of the coal 
heap. 

The answer to the third question is : Two-elevenths 
of the exhaust steam is the greatest quantity that can 
be utilized in the warming of the feed water, and 
making a generous allowance for loss by radiation, 
etc., there Avill still be more than three-fourths of all 
the exhaust steam for other purposes, as was ex- 
plained earlier in this chapter. 

It frequently happens that an engineer, or one who 
sets up an engine, claims that a back pressure is injur- 
ious to the engine and reduces its efficiency or pre- 
vents its valves from working properly, and there 
appears to be an idea among many users of steam 
that it is just as well to take live steam from the boiler as 
to cause 1 or 2 pounds back pressure on the engine, 



EXHAUST STEAM AND ITS VALTTB. 237 

the pressure necessary to get a circulation, and drive 
the air from all parts of tlie pipes and radiators. 

A loss of efficiency there certainly is, but it is small 
and can be offset by an extra pound pressure at the 
boiler, and the general gain is so great that engines 
should be provided a little larger to meet the loss, if 
necessary, though as a matter of fact it is scarcely 
worth considering, as will be shown below. 

The loss in power to an engine from back pressure 
is very nearly directly as the difference between back 
pressure and mean pressure. Thus, in an engine of 
50 pounds mean pressure, with a back pressure of 2 
pounds, there is a loss of 4 per cent, to the engine 
and as the available energy of an engine, together 
with the steam used in the heater, cannot represent 
one-quarter of the practical thermal value of the coal, 
the loss caused by 2 pounds back pressure cannot 
represent 1 per cent, of the coal, and as it is an incon- 
trovertible fact before shown, that the exhaust steam 
contains more than three-fourths, or 75 per cent, of 
the practical thermal value of the coal, the balance is 
immensely in favor of using the exhaust steam, 

I want to guard against an error that may arise 
from the foregoing, and which once came under my 
notice. A back pressure of about &Ye pounds was kepo 
on an engine of about 100 horse-power for the pur- 
pose of warming one radiator of about 40 square feet 
of surface that was in the office of the establishment. 
This, of course, was poor economy, as the radiator 
could condense only about 10 or 12 pounds of water 
per hour — say J to ^ of a horse-power— while the 
drawback to the engine was probably 10 horse-power. 

The exhaust steam from the engines of the present 



238 STEAM HEATING FOR BUILDINGS, 

day varies from 20 to 45 pounds weight per horse- 
power per hour, according to their class, the electric 
light engine of 50 to 100 horse-power using about 45 
pounds of steam, and the Corliss or compound non- 
condensing engines doing the same work for about 
half that weight of steam, while ordinary commer- 
cial radiators condense from J to ^^ of a pound weight 
of exhaust steam per square foot of surface per hour. 
One radiator, therefore, will cause as much or nearly 
as much back pressure as 100 or 500, and of course, 
unless the gain is greater than the loss, we do not 
want such an apparatus. Eemember the loss is al- 
ways about 2 per cent, of the engine power, which is 
a constant, while the gain is variable, depending on 
the amount of heating surface. 

Let us take an example. Suppose one engine of 
100 horse-power with 300 square feet of surface, and 
another engine of the same power with 3,000 square 
feet. The engine uses 40 pounds of water or steam 
to the horse-power, and the drawback or loss due to 
the back pressure is 4 per cent., which in this case is 
4 horse-power, and to make up which we have to evap- 
orate 40 X 4, or 160 jDounds more water from the tem- 
perature of the feed water, say the equivalent of 
160,000 heat units. Now, in the case of the 300 
square feet of heating surface we have 300 X .25, or 
75 pounds of water or steam condensed, the equivalent 
of 75,000 heat units, the gain being 85,000 heat units 
less than the loss ; while with 3,000 square feet of 
radiation we have 3,000 X .25, or 750 pounds of water, 
representing 750,009 heat units, the gain being nearly 
jive times greater than the loss. These figures are 
close approximations to the facts, and any educated 



EXHAUST STBAM-AND ITS VALUK 239 

engineer can work the problem out for himself when 
actual conditions are known ; but before leaving the 
subject it is well to add that the total exhaust steam 
from a 100 horse power common engine doing full 
duty will warm 10,000 to 12,000 square feet of ordi- 
nary radiation. Of course if the engine is only devel- 
oping half its power, the heating surface warmed will 
be in the same proportion, and so on. 

When using the exhaust steam for the warming of 
the feed water alone, it is not necessary to use a back 
pressure valve, as the steam can be made to pass di- 
rectly through the feed water heater on its way to the 
roof or to a condenser. It is different, however, when 
the exhaust steam is to be used in warming a building. 
In such instances sufficient back pressure must be 
kept in the apparatus to force the steam into the dif- 
ferent parts of the apparatus of the building. When 
an apparatus is well and properly piped, 2 pounds 
back pressure is always sufficient for all work of or- 
dinary magnitude. Of course, we often find an appa- 
ratus running nicely with a back pressure so low that 
the ordinary gauge will scarcely respond to it. This, 
however, is generally after the air is expelled from the 
apparatus and everything warmed up, in which case 
I have known the apparatus to run with a pressure 
somewhat below the atmosphere. It is well to remark 
here that back pressure, as the steam fitter knows it, is 
always pressure above atmospheric pressure. Every 
non-condensing engine has to exhaust against the 
pressure of the atmosphere and the resistance of its 
own exhaust pipe. When thus exhausting, they 
actually have a back pressure of the atmosphere, 
about 15 pounds, and when exhausting into a heating 



240 hTEAM HEATING FOR BUILDINGS, 

apparatus the total back pressure is 16 to 17 pounds. 
It is the pressure above the atmosphere, however, 
that is here called back pressure. 

A back pressure valve — the form of which can be 
found in any steam trade catalogue — has to be used 
when exhaust steam is to be confined and forced into 
the pipes of a heating apparatus. There is a means 
of closing it and of loading it to open at any required 
pressure, and for summer use, or when steam is al- 
lowed to pass freely into the air, it can be set open, 
so the steam will escape freely. 

When using back pressure valves, care should be 
taken in their selection. When used in the basement 
of a building, a noiseless back pressure valve should 
be employed, and even when used on roof the noise 
is telegraphed down the pipe and through the pipes 
of the apparatus. 

Buildings are very successfully warmed by steam 
expanded from a high to a low pressure, through 
a regulating valve near the boiler. Into this low sys- 
tem the engines and pumps are allowed to exhaust 
through a suitable connection. Should the quantity 
of steam from the engines, etc., be greater than the 
coils can condense, and raise the pressure slightly, 
the regulating valve at the boiler will close and admit 
no more live steam, and should the pressure still con- 
tinue to increase by the addition of exhaust steam, 
the back-pressure valve at the engine will open and 
let the excess escape to the roof through the summei 
exhaust pipe. This subject will be treated more fully 
in the succeeding chapter. 



CHAPTER XXI. 

EXHAUST STEAM HEATING. 

When the term " exhaust steam heating " is used, it 
implies that the exhaust steam from the engines and 
pumps of a building is admitted to the heating pipes, 
and "an exhaust steam system of heating" implies 
tthat the pipes of the apparatus are arranged, or are 
o be arranged, for the free use of exhaust steam. 

It does not, however, imply a particular method of 
running pipes. Any of the usual methods of piping 
used for low pressure steam will do, so far as the 
running the pipes through a building is concerned ; 
provided, of course, the pipes are sufficiently large in 
diameter. It does, however, imply that proper con- 
nections will, or are to be made between the exhaust 
])ipes of the engines, etc., and the pipes of the heat- 
ing apparatus, and that proper provision will be made 
for taking care of the condensed water. 

When the exhaust steam from the engines, etc., is 
not sufficient to warm the building, but is still of too 
much importance to be allowed to go to waste, it can 
be turned into the heating pipes of the house or build- 
ing and condensed therein, provided the pressure car- 
ried in the heating pipes is not too great. 

241 



242 STEAM HEATING FOR BUILDINGS. 

Should the boiler pressure be carried in the pipes, 
of course the exhaust steam cannot be turned into 
them. For this reason, therefore, in such apparatus, 
the boiler pressure is reduced by passing it through 
a pressure-reducing valve and thence allowing it to 
pass into the heating pipes at any pressure from -J 
pound above atmosphere upward. 

Under such circumstances we will have two kinds 
of steam in the heating apparatus and pipes, live 
low pressure steam from the boilers and exhaust 
low pressure steam from the engines. As the 
exhaust steam from the engines or pumps .varies 
in quantity as the work they do varies, the low- 
pressure steam from the boilers is made to respond 
automatically and supply the loss, and thereby keep 
a constant supply of mixed steam at a constant 
pressure in the heating apparatus to supply its de- 
mands, whether they are constant or intermittent. 
The large office buildings of New York and the large 
cities are now nearly all done on this principle, and I 
will, with the aid of the diagram, Fig. 91, endeavor to 
show the simplest form of such an apparatus, and am- 
plify as I proceed, taking up and explaining the nee 
essary functions and uses of the different parts of the 
apparatus as they are reached. 

The boilers a a are shown at the left in perspective, 
with the style of connections usually employed with 
horizontal shell boilers. One set of the connections, 
h b, connect in'o a cross main c — usually of con- 
siderable diameter — from one or both ends of which 
live high-pressure steam is taken to the engines or 
pumps, or any place where high pressure steam is re- 
quired. In this case I show the pipe d, connecting 



EXHAUST STEAM HEATING. 



24; 



with, say, an electric light eugiiie, the exhaust pipe, e, 
of which, runs first to a feed-water heater, through 
vv'hich it can be made to pass directly by the pipes 
?ind valves g and g , or it may go forward to the roof 




244 STEAM HEATING FOR BUILDINGS. 

pipe % or to the grease separator/, and the housepipe 
^, by the by-pass and valve h, without the resistance 
of the feed water heater. 

I will digress here to say a few words about feed 
water heater connections, as they are usually a part 
of an exhaust steam heating apparatus. It is always 
desirable to pass the exhaust steam either to the roof 
or to a heating apparatus with the minimum of re- 
sistance, in other words, back-pressure. Approxi- 
mately only one-fifth of the exhaust steam can be 
utilized in the feed water heater. If four-fifths of the 
steam is allowed to pass through the by-pass and 
one-fifth through the heater by the manipulation of 
the valves g, g and A, this is accomplished without 
detriment to the temperature of the feed water and 
with the saving of a very considerable amount of re. 
sistance, as the tubes of a heater offer a resistance to 
the passage of the whole quantity of the steam that 
can hardly be appreciated, therefore the by-pass li 
should be provided, through which the four-fifths of 
the steam is allowed to pass freely on its way. 

From the pipe Z, therefore, in the diagram, the 
steam can pass to the exhaust pipe i, and the back 
pressure valve i to the roof, or it may be allowed to 
pass into the grease sejDarator j, as shown. In the 
summer time the back-pressure valve is held open, 
usually by simply changing the weight to the op- 
posite end of a lever, and the exhaust steam is allowed 
to pass freely to the roof, the valve on the grease 
separator being shut. In the winter time the back 
pressure valve is loaded down to the desired resist- 
ance and the steam is allowed to pass into the grease 
separator j on its way to the heating apparatus 



EXHAUST STEAM HEATING, 245 

Should the steam used by the heating apparatus be 
less than that passed through the engine or engines, 
the surplus will pass off bj the back-pressure valve i 
and the exhaust pipe, the back-pressure valve acting 
as a safety or escape valve. 

It sometimes happens that the exhaust steam is less 
than the heating apparatus requires, even in moderate 
weather, in which case a gate valve can be put into 
the exhaust pipe i, just below the back-pressure 
valve. This is an assurance that all the exhaust 
steam passes into the heating mains and that none 
of the live steam can escape by way of the heating 
mains, grease separator and exhaust pipe. 

The exhaust steam as it passes through an engine 
takes up the cylinder oil and carries it forward in 
volatile and finely divided particles. It is absolutely 
necessary that this oil be separated from the steam 
before it passes into the heating pipes, and later on the 
subject will be treated of more fully. It is sufficient 
for our purpose here to show its usual position/ 

From this grease separator or tank the exhaust 
steam passes to the heating pipes, more or less freed 
from its grease. It passes out through the pipe h, 
with its stop valve X'^, and sometimes with a check 
valve h^. 

The check valve is my own arrangement, and I 
have never met with it except in my own work or 
work for which I drew the specitication. The check 
valve, when one is used, must be noiseless and of kind 
to open with small resistance. Its object is to prevent 
live steam from passing backwards from the heating 
mains m through the grease tank, and thence through 



246 STEAM HEATING FOR BUILDINOS. 

the exhaust pipe to the roof, an occurence of consider- 
able frequency, caused by carrying a too great pres- 
sure in the heating mains, when the latter is supplied 
by direct steam through the reducing pressure valve, 
or by the reducing pressure valve becoming temporar- 
ily disordered. When the check valve is used with a 
temporary disorder of the reducing valve, or the re- 
ducing valve being set at a higher pressure than the 
back-pressure valve, the excess of steam in the heating 
apparatus cannot escape, but withal the back -pressure 
will not be increased on the engine, as its exhaust 
steam will be free to escape through the back-pressure 
valve and the free exhaust pipe. 

The pipe represented by m m is the main steam- 
heating pipe, from which all branches of the heating 
apparatus ramify, and from this point I will return 
to the domes of the boilers and trace the live steam 
from the boilers to the heating apparatus. 

The pipes n n are dome connections, with their 
valves. They connect with a cross-main o when there 
is more than one boiler. From this cross-main is 
usually run a connection of sufficient diameter to 
easily supply the heating apparatus with steam, even 
at very low pressures, to be used for night heating 
or when the boilers are run for heating alone and the 
eugines stopped. 

The water of condensation from an apparatus of the 
class I am describing is usually returned to the boil- 
ers by an automatic pump or its equivalent, therefore 
in practice, when the boilers are used for heating 
alone, a pressure is carried suitable for running the 
pump, say 10 pounds. This, then, would be the low- 
est ordinary pressure used in the boilers, and when it 



EXHAUST STEAM HEATINa. 247 

is desirable to pass this steam into the heating mains 
at full pressure the direct pipe and valve p is opened. 

When there is a high pressure in the boilers, how- 
ever, say 80 or 90 pounds or more, and the engines are 
running, it becomes necessary to admit only sufficient 
live steam to make up any deficiency of exhaust, or 
to supply live, should the engine be stopped for the 
noon hour or for other reasons. In a case of this kind 
the direct pipe valve p is closed and the two valves 
q q are opened. The- pipe and valves q q, form the 
reducing pressure connection in combination with the 
reducing-pressure valve r. The pipe starts from a 
tee on the boiler side of the main heating valve 
p, and returns into the main steam-heating pipe 
m at any suitable position in the house side of the 
valve p. 

This connection is usually of a smaller diameter 
than the main pipe. If the main is 6 inches it may 
be only finches or 3 inches, half the diameter being 
fair practice. It is necessary, however, to get a size 
and make of valve that will not sing, and the length 
of pipe from the reducing valve to the main steam 
pipe should be as short as possible, or if it cannot be 
made short, it should be increased in diameter. The 
reason for this is, should the pipe from the regulating 
valve be of small diameter and long, its own resist- 
ance when passing much steam will create a fictitious 
pressure at the valve, which resistance will vary as 
the demand becomes greater or less, causing a varia- 
tion of pressure at the low pressure end of the regula- 
tor, and creating the impression that the valve is not 
constant. 

There are pressure-reducing valves in the market 



248 STEAM HEATING FOB BUILDINGS. 

that are remarkably accurate, the pressure of the 
steam on the low pressure side of the valve controlling 
the valve and keeping the pressure constant, no mat- 
ter what the range of pressures may be in the boiler. 

Valves q q are placed at each side of the regulating 
valve. This is so the high pressure from the boiler 
and also the low pressure from the heating mains 
may be shut out of the valve, that it may be adjusted 
or repaired. As above described and set, the valve 
will go on supplying steam through the pipe m 
to the remainder of the apparatus when it re- 
quires it, and closing automatically and retaining its 
steam when the supply through the exhaust con- 
nection is more than the heating apparatus can 
condense. 

This subject would not be complete unless the 
manner of disposing of the condensed water was at 
least briefly described. 

As I said before, any of the low pressure systems of 
piping will do for an exhaust system. Where there is 
a water-line system, with all the return pipes carried 
below a water-line, the grease collects in the vertical 
jnpes at the Avater-line, provided grease is allowed to 
remain in the steam ; and the general assumption can 
nearly always be that a little grease will always get 
through the grease separator. Of course the frequent 
blowing out of the system will remove this grease or 
oil; still I am of the opinion that the small separate 
return system of piping should not be selected for 
an exhaust steam apparatus when a large single return 
pipe, even if it is trapped by a water-line, can be 
selected. Still I would not advise the tearing out 
and altering of a system of small separate returns, 



EXHA UST STEAM HEATING. 249 

that is otherwise in good order, should one be called 
upon to alter it into an exhaust system. 

When the receiving tank or pump governor recepta- 
cle can be placed sufficiently low, it will remove the 
water-line entirely, and thus do away with the diffi. 
culty, though in most cases there is not sufficient 
height in basements or cellars to place the tank so low 
that the w^ater will drain into it, instead of overflowing 
into itj as we usually find it. 

In the diagram, Fig. 91, the pipes s s s are the 
return pipes. They are further distinguished by a 
broken line through their center. They are shown 
overhead or in close position to the steam (flow) pipes 
m m. This, however, is not material, and they may 
be on the floor and overflow into the tank or receiver 
of the pump governor t. 

The tank or receiver is provided with a float, which 
controls the supply of steam to the pump u. The 
methods used are various and cannot be shown here, 
but the principle is simple. Usually a water-gauge 
glass is used on the side of the receptacle t to indicate 
the level of the water, which is kept near the middle. 
When the water runs in through the pipe s, the float 
is elevated, and this in turn operates the throttle-valve 
of the pump, which opens and allows the pump to 
run. When water comes down rapidly, the pump runs 
all the faster, as the float is held higher. When it 
comes down slowly the float sinks, and the pump 
^'creeps," as it is often called. This keeps the pump 
hot and always ready for immediate rapid action 
when an intermittent flow of water comes, which 
often seems to be the rule. 

Pumps for this work should not be too large. 



250 STUAM HEATING FOR BUILDINGS. 

About 60 strokes per minute, when the maximum 
work is being done, is good practice. Duplex or some 
order of pumps that are always in action without at- 
tention should be used. 

From the pump the water is forced into the boilers 
in the usual manner, and generally through the feed 
water heater. The pipe v v shows its usual course. 
The steam and exhaust pipes of the pump are omitted, 
but they are similar to those of any other engine. 
They start from the pipe c or d, and return to the 
exhaust pipe e, if possible, at a point before the latter 
pipe reaches the feed water heater. 

There are other arrangements of the apparatus than 
those I show in the diagram. All the essential fea- 
tures, however, are covered. The modifications often 
include the placing of the grease separator before the 
feed water heater. This prevents the grease from 
going into the feed water heater in considerable quan- 
tities. However, it brings the grease separator into 
use the whole year, summer as well as winter. There 
is no objection to this if the grease separator is well 
covered, and there may be an advantage in keeping 
the grease out of the heater. I generally arrange my 
own form of grease separator, which is a comparatively 
large tank, so that the exhaust steam passes through 
it at all times. As it is a large receptacle, the engines 
exhaust into it freely, and it acts as a cushion, taking 
the pulsations of the engines off the heating pipes 
and allowing a constant flow of the exhaust steam 
into the system. Under the head of grease separa- 
tion I will show methods of connections, etc. 



CHAPTEK XXII. 

THE SEPARATION OF GREASE FROM EXHAUST STEAM. 

Where the exhaust steam is used for heating and 
the water of condensation from the heating system is 
returned to tlie boiler, it is found to carry along with 
it a portion of the oil which has been used in steam 
cylinders of the engines as a lubricant. Opinions do 
not now vary as to the effect on the boiler, though the 
result in different cases depends upon the quantity 
and quality of the lubricant getting into the boilers, 
the quality of the water and the chemical composition 
of the various dissolvents or " scalers " employed to 
free the interior of the boiler from sediment. These 
combinations are so varied, and the trouble from this 
source is so dangerous and expensive, that a safe 
rule is to avoid the main cause of danger, the intro- 
duction of oil or grease, to the boilers. 

The boilers in the Eogers building of the Massachu- 
setts Institute of Technology in Boston were destroyed 
a few years ago by grease that was carried into them 
from the neighboring new building of the group. The 
contractor used the exhaust steam and provided no 
means of separating the grease from it, and until the 
injury was done, no one was aware of the mischief 

251 



252 STEAM HEATING FOR BUILDINGS. 

that was going on. They now use a grease separator 
of the kind first nsed and designed by myself. 

In New York we have had several grievous cases of 
the same kind in office buildings and hotels where 
improper or no grease separators were used, and 
much damage is being done all the time by improper 
apparatus. Small apparatus oE the "turkey gizzard " 
order will not take sufficient of the oil and grease of 
the steam. They may remove 80 or 90 per cent, of 
the oil, but the remaining 10 to 20 per cent, is suffi- 
cient to cause the burning of the boiler, particularly 
if it is a shell boiler wherein the heavy " slugs " of 
grease can gravitate to the hottest part of the shell of 
the boiler, the bottom, and become attached thereto. 

An essential feature of any grease separator to be 
be effective is size. Small convoluted or corrugated 
bulbs or globes will not remove sufficient grease. 

The steam passes over their rubbing surfaces with 
too much velocity and carries the particles of grease 
forward with it, almost with the same ease that it 
carries them through the exhaust pipe of the engine. 

The only method I have found to be certain in 
grease separation is to project the steam on the sur- 
face of a body of water in a large tank. The water 
may be comparatively hot, as hot, in fact, as the steam 
can make it, still it will hold the oil, if it once reaches 
its surface. As I said before, however, size, is an im- 
portant element. When a small confined apparatus is 
used, the velocity of the steam through any part of it 
is comparatively little less than through a section of 
exhaust pipe itself. 

When the steam has a rapid motion it forces the 
particles of grease along with it, holding many of them 



SEPARATION OF GREASE, ETC. 



253 



in suspension and forcing those that have already 
been deposited by contact with the sides or ribs of 
the apparatus along with it also. It thus carries it for- 
ward into the pipe again and thence into the heating 
apparatus; whence it is carried to the boiler with the 
" return " or condensed water. 

This makes two essential points, therefore, neces- 
sary for a thorough grease separator, when grease has 
to be separated from steam. The fact is to project 
the steam and grease against the surface of the water, 
and the second is to slow down the velocity of the 








Fig. 92. 

steam as it passes on its way to the outlet. The first 
is easy enough, but at first thought, the second may 
not be so apparent. It is done, however, by enlarg- 
ing the receptical through which the steam passes. 
When the use of exhaust steam in New York build- 
ings began to become general, the j^roblem was pre- 
sented to me, and I conceived the idea of a tank of 
comparatively large size, at the bottom of which was 
held a quantity of water of about one-third the capac- 
ity of the tank. Into this at one end the steam was 
made to enter at the top, so as to throw the particles 
of oil and water held in suspension directly down- 



254 STEAM HEATING FOR BUILBING8. 

wards and against the surface of the water. It was 
necessary, however, to prevent too great a commotion 
in the tank and to slow down the velocity of the steam 
as it passed away from the surface of the water. So 
to do this the tank was enlarged in diameter until the 
steam in passing through it, was comparatively quiet. 
I use tanks arranged as shown in Fig. 92. 

I find that an 8-inch exhaust pipe to a 48-inch tank 
placed on its side, is about the safe limit of propor- 
tions. The tank's length should be about one and a 
half times its diameter and the flanges as near the ends 
as possible. 

When room is a considerable object, I use a tank 
on its end as shown in Fig. 93. The distance from 
the inlet to the outlet is less than with the horizontal 
form, but the area of the tank can be increased by its 
length, which is only limited by the height of the 
basement or cellar of the building. 

With tanks like the above there is no difficulty 
in reducing the velocity of the steam to one-thir- 
tieth or one-fiftieth of what it has in the pipe, and 
under such conditions the projection of the particles 
of the grease against the water appear to be unaffected 
by any tendency of the steam to find a short cut to 
the outlet. 

Another advantage such an apparatus has, is that 
it takes the violent pulsations of he engine off the 
back pressure valve and aids materially to stop the 
noises that are communicated to the walls and floors 
of a building by the quick running electric engines. 
The illustrations Figs. 92 and 93 have the same ref- 
erence letters. A is the exhaust inlet from the en- 
gine ; B the exhaust outlet to the outside or the heat- 



SEPARATION OF GREASE, ETC. 255 

ing system ; c, the lighter oils floating upon clean, hot 
water ; d, hot water ; 6, sediment ; D, a dam to prevent 
the oil returning and overflowing the bars E ; E, bars 
for the same purpose ; F, inverted overflow pipe and 
water level ; G, anti-syphon pipe ; H, pipe to the 
blow-off-tank or sewer ; L, blow-off valve : M, over- 
flow valve ; I, back pressure ^alve ; J, check valve 
controlling heating system. The body of the sepa- 
rator is made of about J inch iron. 

The operation of the apparatus is as follows : The 
exhaust steam from the engine enters the separator 
through the pipe A, and is projected directly on the 
surface of the water already contained in the tank, 
the oil and water settling at their separate and 
natural levels, and the steam turning upward and 
outward through the pipe B to the external air or 
the heating system. When the water has reached 
the overflow level, it will continue passing up 
through the inverted overflow pipe F, which al- 
ways draws its supply from the lower end, being 
sufficiently submerged to be below the floating oil. 
This keeps a constant level in the apparatus without 
attention on the engineer's part, excepting to draw 
the contents of the apparatus off now and then, once 
a week or a month as the case may be, through the 
pipe and valve L. The regular overflow through the 
pipe F and valve M is clean water that will not clog 
or effect the pipes. The action is continuous as long 
as the engine is running, the accumulation of water 
simply overflowing. The function of the pipe G is to 
prevent syphonage. Without it the pressure in the 
tank would charge the pipes F and M and syphon 
the entire contents away. 



256 STEAM HEATING FOB BUILDINGS. 

By the arrangement of the dam D and the cells 
formed by the bars E, clear water is always exposed 
to the greasy stream as it is projected downwards. 
The entrained water in the steam has already collected 
the grease, so that the globules of water and grease 
are thrown on the water in the ceils between bars. 
The impulse of the steam depresses the level of the 
water in the cells and compels it to move towards the 
overflow end at F. The return wave of the water is 
at the surface, and flows in the opposite direction 
against the dam, over which it does not go. The con 
tinned pulsating surface of the water between the 
bars tends to force the oil to the opposite side of the 
dam, thus always presenting a fresh clean surface of 
water for the reception of the oil. 

The exhaust steam, freed of its oil, passes out 
through the pipe B and valve T for use in the heat- 
ing system, and when condensed can be safely re- 
turned by the feed pump for further use in the boiler. 
The small amount of water deposited and wasted from 
the separator does not repay an effort to return it to 
the boiler, though it may be of value for other uses, 
and in some cases it is used and allowed to overflow 
into the open tank of the hydraulic elevator system, 
where the greasy water is found to be a considerable 
factor in keeping the hydraulic cylinders in good 
order. 

In cleaning the separator, the stop valve M is 
closed and the sediment valve on the bottom is 
opened, when the pressure will purge it. 

Of course if the water from the separator is to be 
utilized, a separate connection to the sewer should be 
provided for use in cleaning. 



BEPABATION OF GREASE, ETO, 



25" 




Fig. 93- 



258 



STEAM HEATING FOR BUILDmGS. 



To make the apparatus entirely automatic a " Eoyal " 
steam trap can be introduced into the pipe M and 
allowed to waste into the pipe H. A water glass may 




Fig. 94. 

be placed on the side of the apparatus to show at a 
glance the level of the water. 

The position of the grease separator is an important 
question. In the foregoing chapter I show it follow- 
ing the feed water heater. Some prefer to place it in 



SEPARATION OF GREASE, ETO. 259 

the system in such a manner that the steam will pass 
through it before it passes through the feed water 
heater. There may be some advantage in this by 
keeping grease out of the heater. All heaters, how- 
ever, play some part in the separation of grease 
from steam, and were it not for this fact alone, there 
would be a great many more burned boilers in our 
city buildings. Of course when the feed water heater 
is on a branch of the exhaust pipe it cannot act as a 
grease separator to any appreciable extent. 

Fig. 94 shows a combined grease separator and feed 
water heater which I designed. The steam is first 
projected against the water and then allowed to pass 
through the feed water heater, which is suspended 
directly in the grease separating tank. It saves in 
cost and room, makes a very efficient heater and it is 
supposed by some to take exceedingly fine particles of 
oil out of the steam that may by some means escape 
the water. In the Manhattan and Merchants' Bank 
Building, 40 and 42 Wall street, New York, one of 
these water tank grease separators can be seen where 
it has been in use since 1886. 

The water of condensation is collected in a receiv- 
ing tank, and in all those years no grease has ac- 
cumulated in the receiving tank, not to consider the 
boilers at all. 



CHAPTEE XXIII. 

BOILING AND COOKING BY STEAM, AND HINTS AS TO 
HOW THE APPARATUS SHOULD BE CONNECTED. 

Lakge institutions witli many inmates find it almost 
impossible to cook without the aid of steam, and man- 
ufacturers have long since abandoned all externally 
fired kettles for this purpose. Of the superiority of 
steam as a means of drying and cooking, there is no 
question, and the occasional failures which occur 
should not be attributed to steam, but to errors in the 
construction of apparatus, and an ignorance of their 
use. Satisfactory appliances are within the reach of 
the steam-fitter, though frequently the ruinous compe- 
petion in small things, which compels the lowest bid- 
der to neglect and omit everything possible, or in 
other words, " to do the least for the least money,'* 
ruins the effect of otherwise successful machines. 

The first and commonest kind of cooking by steam 
is " steaming," which is again divided into steaming 
in the atmosphere (or at atmospheric pressure), and 
steaming under pressure in closed tanks or boilers. 
Steaming can be used in the preparation of anything 
into which water cannot enter or become part of, 
as oils, or of substances which want an addition of 

260 



BOILING AND COOKING BY STEAM. 



261 



water, but are capable of taking up only sufficient 
water to properly prepare tliem as vegetables, or sub- 
stances which want to be bleached or disintegrated, 
as rags. 

The simplest form of steamer is the ordinary kitchen 
steamer ; a wire basket or tin pot with holes in the 
bottom of it, suspended in a larger pot with water in 
the bottom of the latter, the water not reaching the 




Fig. 95. 

bottom of the basket. The steam, rising and mixing 
with the air in the basket, gives a uniform heat when 
the water in the lower pot is boiling. 

It is well known to the intelligent cook, that vegeta- 
ble-cooked this way can be done through without 
breaking or without losing any of their starch. This 
cannot be done in boiling water, as the mechanical 
action of the water during ebullition breaks and 
washes out part of the substances before they can be 
sufficiently cooked in the center. 



262 STEAM HEATING FOB BTflLDmOS. 

The modification of this simplest kitchen steamer, 
used in large buildings, such as hotels and public in- 
stitutions, is shown in Fig. 95. 

The outside case, A, may be of cast-iron, or sheet, 
iron riveted and soldered with a cover of sheet-iron. 
The baskets, B B, rest inside the outer case on a 
perforated shelf, C, and are usually made of heavy 
tin plate, with holes in the bottom for the condensed 
steam to run off. 

The connections to these steamers require particular 
attention, far more than would appear from a superfi- 
cial examination. The condensed water which gathers 
in the bottom of the outside case should be carried to 
the sewer or drain, and must be connected in such a 
way that the foul air of the sewer cannot return into 
the steamer and contaminate the food. And as much 
— and more — attention should be paid to the waste 
connection from a vegetable steamer than is paid to 
the connections from a wash basin, even in a sleeping 
room. It is not only essential how the connections 
are run, but from what material they are composed, 
and further, how the joints are made, and from what 
material. 

As the steam and hot water are capable of destroy- 
ing lead pipes and traps, or working the lead joints 
out of cast-iron pipes, it is best to use either wrought- 
iron screwed pipe, or cast-iron pipe with rust joints, 
using a very deep S-trap, constructed of fittings, with 
plugs at every corner, so as to get straight openings 
at every part of the pipe, by simply removing the 
plugs. This is necessary to remove grease, or any 
obstruction that may pass into the pipe. The 
pipes should be of large diameter (about 3 inches) 



BOILING AND COOKING BY STEAM, 263 

with the trap sufficiently deep to prevent the pres- 
sure of steam within the steamer from blowing it 
out, and connected with some contrivance, vacuum 
valve or vent pipe, run on approved sanitary princi- 
ples, to prevent its siphoning out, as is common to all 
soil pipes. 

There is another source of contamination or poison 
in the connections of vegetable steamers, or any other 
steam boiler, which must have a vapor pipe. These 
pipes should not be constructed of galvanized iron or 
copper, or any other substance whose salts are poison- 
ous, as the condensation w^hich takes place within this 
vapor pipe falls back into the kettle, continually 
washing down carbonate or sulphate, or whatever may 
be formed, that yields easily to the action of pure 
water. These pipes should be constructed of iron 
gas pipe, with screwed joints, or cast-iron pipes with 
rust joints. 

The live steam connection to an open steam box or 
steamer should be very small. Usually a f or J-inch 
pipe is used, and there is no discretion exercised in 
the manipulation, but an endeavor made to cook as 
rapidly as possible, regardless of steam. Beyond a 
certain quantity of steam admitted, nothing is gained 
in time, as just steam enough to expel the air is all 
that can be used ; a greater supply is only wasted 
through the vapor pipe, or escapes into the kitchen 
under the edge of the cover. 

There is another point in the construction of open 
steamers worth considering, namely, a water seal 
around the edge of the cover. The seal consists of a 
groove or channel around the top edge of the case, 
into which a rib around the under side of the cover 



264 



STEAM HEATING FOR BUILDINGS. 



fits, as can be seen at a', Fig. 95. This seal sliould be 
as deep as possible, and to be effective sliould run 
around the whole cover, and not be dispensed with 
on the side of the hinges, as is frequently done. The 
object of this water trap, or seal, is to prevent steam 
from escaping into the kitchen and to force any excess 
of pressure out through the vapor pipe. To get the 
greatest economy, the water seal should be 2 inches 
or more deep, with a small sized vapor pipe with a 
valve in it, so it can be choked down to hold a pres- 
sure in the steamer, but not enough to force the water 
seal. 

Steaming under pressure must be done in a closed 




Fig. 96. 



b*:>,jler of tight tank capable of resisting high pressure 
steam. A common form of ^ this class of steamers is 
the rag boiler in the paper mill. It is a horizontal 
cyliudor, with conical ends, supported on trunions, 
and mada to revolve by machinery, so as to use the 
mechanica,! motion in assisting the disintegration of 
the rags. This boiler is shown in Fig. 96, and should 
be constructed of exceedingly heavy iron, or it may 
explode and do much injury. The pipe connections 



BOILING AND COOKING BY STEAM. 



2^1 



are made at the ends of the tr unions, Of, which are 
provided with stuffing-boxes revolving around the 
pipe, thus leaving it stationary. 

Another form of high pressure steamer is an upright 
tank of strong construction, in 
which fats are rendered and separ- 
ated by the action of high pres- 
sure steam. This tank is shown 
at Fig. 97, and is often 20 to 30 
feet long. The fats and oils stratify 
according to their gravity, with the 
water of condensation underneath, 
and are drawn off at the numer- 
ous cocks, according to their qual- 
ity. 

The steam connections on these 
tanks are made at the top and 
bottom, and they are sometimes 
constructed with a spiral coil near 
the bottom. 

Cooking and manufacturing by 
the transmission of steam heat 
through metal surf-aces and not by 
direct contact, as in steaming, re- 
quires apparatus of varied designs, 
often the result of years of ex- 
perimenting, the following modifi- 
cations being the most common 
Figs. 98 and 99 shows sections of two of the ordi- 
nary forms of double-bottomed steam cooking kettles. 
The various uses to which these kettles are applied 
are wonderful. Differing very little in shape, the size 
alone adapts them to the special use. Small sizes, 20 




Fig. 97. 



266 



STEAM HEATING FOR BUILDINGS. 



to 40 gallons, can be used for glue melting, etc. ; sizes 
running from 60 to 100 gallons are mostly used in 
hotels and institutions for cooking meats and farina- 
ceous foods, and larger ones, up to 500 gallons, are 
used in sugar-houses and soap-boiling establishments. 

Sizes to 200 gallons are usually cast-iron, but larger 
ones are often made of wrought iron, riveted and 
calked. 

The connections to these kettles are plain, but the 




Fig. 98. 



Fig. 99. 



steam pipe should be large, and the return water pipe 
should not be put back into a return gravity circulation 
apparatus, but should be carried away by a good steam 
trap of approved pattern. 

Yapor pipes from these kettles should be of iron, 
for the same reason mentioned in connection with 
" steamers.*' 

The pipe from the inside of the kettle, which carries 



BOILING AND COOKING B7 STEAM. 



26' 



the contents to a receptacle or sewer, should be large, 
with tees and plugs at every right angle, instead of 
elbows to permit of easy and rapid cleaning should it 
get stopped with grease or any other substance which 
hardens on cooling. 

In these kettles steam cannot be wasted unless it is 
passed through a defective steam trap, the consump- 
tion of steam depending on the amount of work to be 
done and the radiation from its outer sides. 




Fig. icxD. 

This radiation is often partly prevented by an out- 
side loose jacket, and if the space between the jacket 
and the kettle is filled with some non-conducting ma- 
terial, the loss of heat from the outside of the kettle 
will be reduced to a minimum. 

There is another class of kettles or pans which are 
not double-bottomed, but boil and cook by steam heat 
transmitted through spiral oils, passed around the 
inside of the bottom, the pan itself being partially ex- 
hausted of atmosphere in order that the contents may 



268 STEAM HEATING FOB BUILDINGS. 

boil at a temperature mucli below 212° Fahr. These 
kettles or pans are usually very large, and are princi- 
pally used in sugar-bouses and condensed milk estab- 
lishments, or any place where boiling or evaporating 
at very low temperatures is desired. 

Fig. 100 shows a section of one of these pans. The 
principal point of importance to , the steam-fitter or 
coppersmith are the sizes of the pipes and the man- 
ner in which they should be run. 

When a quantity of water is to be raised from ordi- 
nary temperatures (35° to 55° Fahr.) to boiling, it must 
be borne in mind by the fitter, or constructor, that it 
will take in steam at least ^ of the weight of the water 
in the pan to raise it to the boiling point, and that 
when steam is first turned into the space between the 
bottoms of jacketed kettles or into the spiral coils of 
tanks or vacuum pans, the shrinkage, i. e., condensa- 
tion of the steam, for the greater differences of tem- 
perature is something enormous, and unless the sup- 
ply of steam is continuous and high and the pipe 
which conveys it ample for the greatest amount of 
work that can be put on it at any one time, the result 
will be the filling up of the space or coil with water. 

This is a point of more importance than appears at 
first. It is a common thing to find a stock-boiler or a 
kettle of any kind that will not begin to boil for hours 
after steam is let on, provided the kettle has been 
filled Avitli water before the steam was turned on. It 
is also found that should the steam be turned on first 
and the water run into the kettle gradually after- 
wards, that in most cases, by the time the kettle is 
full, it will also be boiling. Now the reason is plain 
enough upon a little consideration. When the kettle 



BOILING AND COOKING BY STEAM. 269 

is full of cold water it is in a condition to be a good 
condenser, and when tlie steam is let into the coil or 
steam space, it is instantly condensed and there is a 
vacuum or a very small pressure within the coil or 
steam space. This prevents the condensed water from 
running off into the condensed water pipes, where 
there is always considerable back pressure, and thus 
the coil or space becomes filled with slightly warm 
water, while the kettle is filled with cold water. This 
forms a deadlock for a time. The steam, however, 
ceases to condense when it cannot pass into the coil 
or steam space, and then its pressure asserts itself and 
a little of the water is forced out of the coil and into 
the return pipe ; but only a little, for just as soon as 
the steam meets the cold water again its pres- 
sure is reduced and a very small part of the coil only 
is active, the upper part, or the part near the inlet. 
This goes on for an hour or two or three, and then the 
steam gradually overcomes the cold of the water, as 
the condensing power of the water becomes less. 

Of course if the pressure of steam is great enough 
and the pipes very large, the steam will assert its in- 
fluence quickly. We are therefore to use as large 
pipes as practicable in such cases, and coils of large 
diameter and a few turns in preference to long coils of 
small diameter pipe. 

With small inlet pipes and coils the trouble may be 
overcome by turning on the steam and admitting the 
water slowly, but this cannot always be practicable. 

Long, flat wooden vats, with a coil of any convenient 
shape, in the bottom, are often used for the evapora- 
tion of the water from brine by the salt manufacturer. 
Exhaust steam from neighboring engines can be used 



270 



STEAM HBATINO FOB BUILDINGS. 



here to advantage, thus utilizing heat that would other, 
wise be lost. 

Another common way of warming or boiling water, 
when the object is not evaporation, but the warming 
of a tank of water for laundry purposes, or when the 
addition of the condensed steam is a benefit (provided 
it is not greasy), is to put the steam pipe directly into 
the water in the form of an open butt or a perforated 
coil. This mode is usually attended with noise, but 
it is quick and effective. 

When a perforated coil is used, it is usual for the 




Fig, loi. 

fitter to have as many small holes in the coil as will be 
equal in the aggregate to the area of cross-section of 
the pipe in the coil, but in practice this is not nearly 
sufficient, if he wants to pass out all, or nearly all, 
of the steam and water which the supply-pipe is cap- 
able of passing. 

AYithin an empty pipe, steam has a very high veloc- 
ity, but striking the water as it passes the holes re- 
tards it so much that five to ten times the area of the 
pipe in small holes has not been found too great in 
practice, the time of boiling lessening rapidly up to 



BOILING ANi) COOKING BY STEAM, 271 

ten times with shallow water and forty pounds of 
steam. 

The pressure of the steam and the depth of the 
water affects the time of heating ; high pressure acceh 
erates and deep water retards it. 

The lower the pressure of the steam that will pass 
out, as it strikes the water, the less the noise will be, 
and a good way to avoid noises is to have a coil or pipe 
of large diameter in the water, with a great many small 
holes in it, letting the high pressure steam expand 
into this perforated pipe through a " throttled " valve^ 
until the desired low pressure is attained. 

Another way to prevent noise is to place an iron 
cylinder with wire-cloth ends, filled with shot, over the 
end of the steam -pipe, the pipe turned up into the 
cylinder, and the cylinder in a vertical position. 
(See Fig. 101.) 

Still another way to warm water with steam is at 
the nozzle or cock where it is drawn. A very simple 
method is by mingling the steam and the water after 
they pass their respective cocks or valves, as showu at 
Fig. 102. There should be no cock or valve put in 
the bib, a\ for closing it will either force the water or 
steam (whichever has the greatest pressure) into the 
other. Therefore it is necessary to have little or no 
resistance in the pipe after passing the valves. 

A very simple noiseless nozzle is shown in Fig. 103 
It consists of an enlargement after passing the valves 
filled with shot, with a strainer to prevent the shot 
from passing out ; or it may be filled with clean 
gravel or anything the steam and water will have the 
least action on. By the regulation of the valves, a 
steady stream of water of almost any temperature be- 



272 



STEAM HEATING FOR BUILDINGS, 



tween 212° andtlie temperature of the cold water can 
be had. 

Often the pipe -fitter is called upon to construct ap- 
paratus to warm water for bath-houses, laundries, or 
any place where they have no steam and require no 
power, hence do not wish to have a steam boiler, but 
nevertheless use more water than can be warmed by 
the ordinary water-back in the stove. The problem 
is then, to warm the largest amount of water with the 
smallest expenditure of fuel. Fig. 104 shows an ap- 





Fig. I02. 



Fig. 103. 



paratus that for permanency and cost of maintenacce 
is very satisfactory. ^, is a tank of any convenient 
shape ; B, a cast or wrought-iron boiler, similar to that 
used for green house heating ; C^ a connection from top 
of boiler to the side of the tank, not very high up, as 
all the water below the point where it enters the tank 
cannot be estimated as part of the working capacity 
of the tank, for it is necessary to always keep this 
pipe covered with the water ; D, the return pipe from 
the tank to the boiler, its inner end being carried a 
few inches above the bottom of the tank to prevent 



BOILING AND COOKING BY STEAM. 



273 



sediment from being carried into the boiler; and E 
the pipe leading from the tank for the distribution 
of the hot water, the position it occupies being im- 
portant, as it must always be above the pipe C^ to 
prevent the possibility of drawing the water in the 
tank entirely down to that point. 

The tank may be furnished with a ball cock to the 
cold-water pipe, as shown at F, to keep a constant 
level of water. 

By feeding the water into the tank instead of into 




Fig. 104. 

the boiler, impurities are deposited in the bottom of 
it instead of being carried into the boiler. The same 
is true of all hot water apparatus, if the bottom of the 
tank is below the return pipe, with capacity enough 
in the tank to prevent rapid currents. 

The above is one method often used in warming 
swimming baths. A boiler of the hot water pattern 
is set up at some convenient part of the building, 
below the swimming tank, and circulating pipes C 



274 STEAM HEATING FOB BUILDINOB 







BOILING AND COOKING BY STEAM. 275 

and D are connected with tlie tank. The tank may 
be of any desired shape and size, but otherwise the 
apparatus is the same as that shown in Fig. 104 

Although the foregoing method is often used for 
warming large tanks of water, it has one objection, 
which becomes greater as the water contains impuri- 
ties. Nearly all the water of the tank is made to pass 
through the boiler at some time, and in doing so it 
deposits mud and other substances it may hold in 
suspension within the boiler. To obviate this an ap- 
paratus similar to Fig. 105 may be used. T repre- 
sents the swimming tank, on each side of which there 
may be one turn of large diameter pipe. The pipe 
should be in a recess r in the side wall, so there will 
be no likelihood of a diver striking his head. In a pit 
at the end of the tank is a boiler B with an expansion 
tank, and in other respects a regular hot-water appa- 
ratus. In such an apparatus the water is always 
the same, and of course there is no deposit of mud in 
the boiler. 

In small apparatus for making hot water, a coil of 
pipe is sometimes used in a stove instead of a boiler, 
but it often fills with mud or lime and burns out. 

Before leaving the question of boiling or cooking 
I will refer to Fig. 106, which shows a pair of steam 
roasting ovens. They are cast-iron with double bot- 
toms and double sides for about two-thirds of their 
heights, the double side forming a terrace or step on 
the inside of the oven. It is within this space that 
the steam circulates. Tight-fitting heavy covers fit 
over one-half the top to retain the hot vapors given 
off by the meats. They are connected similar to an 
ordinary radiator, and are becoming much liked in 



276 STEAM HEATING FOR BUILDINGS. 

public institutions, an oven being capable of holding 
60 to 70 pounds of meat, and cooking it in an hour 
and one half with forty pounds of pressure of steam. 




Fig. io6. 

Meats cooked in one of these ovens have all the 
appearance of a pot roast and will become tender 
when the same part of the animal in the ordinary 
oven will be hardly fit for food. 



CHAPTEE XXrV. 

DRYING BY DIRECT STEAM. 

Three-foubths of all the manufacturers outside of 
the metal trades, and even many of them, use heat for 
drying purposes ; and various as are the manufactur- 
ers, so various are the modes of drying, in many in- 
stances satisfactory results being attained only by 
years of experience. No manufacturer of wooden 
articles can get along without a drying kiln. The 
laundry man or woman, the dyer, the hatter, the shoe- 
maker, the tobacconnist, the piano and organ maker, 
the dried-fruit manufacturer, the japanner, the tanner, 
all must have a means of drying faster and more con- 
veniently than can be had by exposure out-of-doors, 
and even now the common red bricks are often dried 
by artificial heat and forced currents of air when the 
weather is too cold or damp to do it in the open yard. 

Usually steam is used in drying rooms and drying 
kilns because of its cleanliness, its even distribution, 
its safety from fire, its easy and quick management, 
and the cheapness of its maintenance. 

The higher the temperature of a drying room, the 
cheaper can the articles be dried. This may not ap- 
pear plain at first to those who have studied the laws 

277 



278 



STEAM HEATING FOB BUILDIWGS. 



of equivalents, but nevertheless it is so, being caused 
by local conditions, which always prevent the utiliza- 




tion of all the heat. Thus, the greater the difference 
in temperature and the slower the movement of the 



DBTING BT DIRECT STEAM HEAT. 279 

air up to the point of saturation, tlie better the result 
in the laundry or dry kiln, or any place where rapid 
drying only is the object. 

In no other place is the power of radiant heat (di- 
rect radiation) more manifest than in the drying room, 
and more failures can be traced to placing coils under 
skeleton floors, or flat on the floor, than any other 
cause, except, perhaps, an ignorance of the principles 
of piping, which so many consider can be done by any 
one who wears a pair of greasy overalls. 

I have proved, in many cases, that the same amount 
of pipe or plate surface, distributed around and be- 
tween the materials to be dried, will do the work in 
half the time it takes the heated air from an indirect 
coil. This is no mistake ; and further, wooden blocks 
can be dried lighter (proving there is more water 
driven off) by direct radiation than by indirect radia- 
tion, the times and temperature being the same. 

According to the above it is plain that in the con- 
struction of drying houses for most purposes, the heat- 
ing surfaces should be so placed and distributed that 
the direct heat rays from the iron could fall uninter- 
rupted on the greatest surface possible of the mater- 
ials to be dried. 

Fig. 107 shows a perspective of a good arrangement 
of a direct radiation laundry drying room coil, utiliz- 
ing all the radiant heat that is thrown off and giving 
a thoroughly uniform heat throughout the room. A 
A' are lieaders (often called manifolds), usually made 
of extra heavy pipe to admit of tapping and threading 
instead of using T's, for the cost of the heavy pipe and 
the drilling and tapping is very much less, and the 
header better and straighter, than when composed of 



280 



STEAM HEATING FOR BUILDINGS. 



many short pieces of large pipe and the necessary T's. 
(These remarks apply to all large coils.) 

B B are the spring pieces, threaded right and left 
handed ; G C^ the leaves or sections of the coil ; and D 
D, the coil stands. The stands are always in pairs, to 
admit of giving the necessary division and inclination 
to the pipes, and when viewed through the holes look 
like Fig. 108. The dotted lines are the centers of imag- 
inary pipes to show the pitch. When coils are very 
wide in the direction of the length of the headers it is 
well to keep the coil stand 2 or 3 feet from the 
header at that end, to prevent the expansion from 




Fig. io8. 



pulling the screws from the floor. The distance be- 
tween the holes in the standing coil header is usually 
about 12 inches, or as wide as the clothes-horses are 
from center to center. 

The usual way to build these coils is to start at the 
bottom header A, Fig. 107, and to put each leaf, (7, to- 
gether continuously, working upward until the elbow, 
E, is reached; when all the leaves are so far con- 



BRTINO BY DIRECT STEAM HEAT, 281 

structed, with all the elbows looking up, with their 
left-handed thread uppermost, count in and mark the 
right and left-handed spring-pieces B^ then apply the 
upper header A, and screw the whole up as nearly 
alike as possible. Do not.be persauded to do away 
with the spring-pieces and the elbows through 
economy, so as to connect the upper headers 
straight, as in a box coil; if you do you will have 
trouble should you want to take down a single leaf for 
repairs. 

Fig. 109 shows sectional perspective view through a 
laundry drying-room ; a being the coil ; 6, the clothes- 
horse ; c, the suspended I'ail from which the horses 
hang, cZ, fresh air inlet duct ; e, its damper or regu- 
lator;/, ventilator with regulator, usually governed 
by a cord and bell crank, and drawn back by a spring ; 
and g, the space into which the horses are drawn, which 
of necessity must be as long as the horses. This style 
of drying-room gives the direct radiation from both 
sides of the leaf of the coil to the fabrics to be dried, 
and also exposes both sides of a fabric to the direct 
radiation of a section or leaf. 

For high or low pressure steam 1-inch pipe is gen- 
erally used in the coil ; and if exhaust steam is to be 
used the pipes should be not smaller than 1 inch, and 
the total length of any one leaf should not exceed 100 
feet of one-inch pipe under a back-pressure of 1 pound 
at the engine. 

For exhaust steam the upper header should be 
large, 3 inches for 12 leaves of 60 to 80 feet each, or 
about 700 to 1,000 feet in the coil gives satisfactory 
results. This should be increased in porportion to 
the increase in the number of leaves, a 4-inch pipe 



282 



STEAM HEATING FOR BUILDINGS. 



header being enough for a coil of from 1,500 to 3,000 
lineal feet of 1-inch pipe. 




DRYING BT DIRECT STEAM RE AT. 



283 



Unless tiie exliaust steam is carried a long distance 
horizontally, the pipe leading to the header may be 




Fig. no. 




Fig. III. 

one or two sizes smaller than the header, provided it 
is large enough for the engine. 

With steam of high tension, small pipe headers with 



284 STEAM HEATING FOR BUILDINGS, 

T-fittings may be used ; but where the pressure is 
variable, a large header insures an equal distribution 
of steam to all the leaves of the coil. 

Sometime gridiron or floor coils are used on account 
of saving expense, but the same ameunt of pipe in this 
form will not dry clothes as fast as the standing sec- 
tion coil. 

Figs. 110 and 111 show gridiron coils of easy con- 
struction, a a being the manifolds or headers ; b h, 
right and left elbows ; c c, coil pipes right handed, 
and d d, right and left handed spring-pieces. In Fig. 
110 the pitch of the pipes and headers is in the direc- 
tion of the arrows. 

These coils are often used in lumber-drying kilns, 
but the same amount of pipes arranged around the 
walls in miter or wall coils will give a far better re- 
sult, and will not be a receptacle for dirt, as a floor 
coil is, requiring a skeleton floor over it to walk on 
and pile the lumber on. There are places, however, 
for this kind of coil. 

In piano-case manufactories, and where specialities 
in glued or veneered furniture of the best quality are 
made, the workmen are generally supplied with a 
drying cabinet, of a size suitable to the pieces to be 
dried, in which the work is heated before the glue 
is applied, and into which it is again placed to dry 
properly. 

These cabinets are usually rectangler boxes, with 
holes in the bottom and top to allow the air from the 
room to circulate through them so as to carry off the 
moisture. Their steam coils are usually of the grid- 
iron pattern, flat on the bottom of the box, with the 
valves on the outside. Sometimes they are heated 



DRYING BY BIMEGT STEAM HEAT, 285 

indirectly by tlie warmed air conveyed in tin pipes 
from a large coil placed in some favorable position. 
Some manufactures claim the quicker the work can 
be dried after gluing the better it will be. 

In large drying kilns on the direct radiation prin- 
ciple, where pipe enough cannot be put on the walls, 
rows of stancheons should be put up to hang the 
coils on, in such a manner as not to interfere with 
the gangways. 

The tobacconist prefers to dry without artificial 
heat, in a temperature of about 60°, with a rapid 
change of air through the windows. This appears to 
give dryness without brittleness, but at night and in 
damp weather it is necessary to close the windows 
and to get the stock out in time recourse must be had 
to steam coils. A temperature of 130° is generally 
considered ample, and can be easly attained in a dry- 
ing room. 

The additional quantity of pipe necessary to raise 
the temperature of a drying room from 120° to 130°, 
if again added, will not raise it from 130° to 140°. As 
the temperature of the drying room approaches the 
heat of the steam pipe, the heating surface has to be 
enormously increased to obtain an appreciable increase 
of heat in the room. 

With low pressure steam — 2 pounds per square inch 
or thereabouts— it is difficult to obtain a temperature 
above 175° in the drying room, no matter how much 
surface is used, and with steam at 60 pounds pressure 
the practicable limit is about 275° Fahr. 

Before leaving the subject of drying-rooms I will 
add a little data I once obtained by experiment, when 
about to construct a large drying-room in a prison. It 



286 



STEAM HEATING FOR BUILDINGS. 



was necessary to find liow mucli water was driven off 
in the drying-room and to do so I weighed the ch^th- 
ing, dry before washing, and also weighed it after 
passing it through an ordinary rubber wringer. 



Socks (w!)(illea). 
Cotton shirt. . . . 
Undersliirt. . . . . 

Drawers. 

Two sheets 

Pillow-slip 

Blanket 

Towel 



Dry. 



U oz. 

1-4 - 

12 " 
lOi " 
25 " 



54| oz. 
4 " 



Wet. 



9|()Z 
28 
26^ 
2U 
50 
12i 
129 
84 



Water to be 
driven ofif. 



6irOZ 
15| 

lU 
25 

4i 



CHAPTEK XXy. 

DEYINa BY AIR CUKEENTS. 

When evaporation is produced by the direct action 
of steam, as in boiling water, it is a well established 
fact that to drive off 1 pound of water from any sub- 
stance requires the heat of 1 pound of steam. This 
fact forms the basis of computation in arriving at the 
cost of drying. Of course there are other losses due 
to transmission, improper apparatus and wasteful traps, 
all of which must be added when known or. assumed 
when unknown. 

A maker of bricks once came to me for advice as to 
the best method of drying them in winter time, say- 
ing he had been trying some experiments with direct 
radiation steam coils placed under and around the 
stacks of compressed clay. He found the cost was 
enormous and probably prohibitory and wanted to 
know what, if anything, could be done to reduce the 
cost. He explained that his output was 60,000 bricks 
a day and that each brick contained an excess of about 
IJ pounds of water, or 75,000 pounds of water he had 
to get rid of each day. 

His boiler was about 100 horse-power, as boilers 
are roughly rated in boiler makers measurement, and 

287 



288 STEAM HEATING FOR BUILDINGS. 

he had run it day and night, burning 5 to 6 tons of coal 
at $5 per ton, without making any very appreciable im- 
pression on the moisture in the bricks over what they 
could show without any heat. Now this person was 
evaporating about 5,000 pounds of water every hour 
in his boiler, and for 24 hours it would amount to 
120,000 pounds, or about double the water he was try- 
ing to drive from his bricks. Still he was not success- 
ful because the heat could not be applied in such 
sheds, and even with the best of sheds he probably 
would have to evaporate twice the quantity of water 
in the boiler that he could drive from the bricks by 
the condensation of the steam. What was to be done ? 
The answer was, try air. Warm dry air if you can get 
it, if not, such air as you can obtain. 

If air is warmed from 50° Fahr. to 100° it is capable 
of taking ujd approximately 15 grains of moisture per 
cubic foot of air. Of course the air will be cooler 
somewhat by this, but assuming it is still capable of 
taking away only 5 grains of moisture per cubic foot, 
taking into consideration it is cooled to 50° Fahr. in 
doing so, 1,000,000 cubic feet of it is capable of taking 
away 5,000,000 grains or 1,000 pounds of water. Now 
it was necessary to take away 75,000 pounds of water 
in 24 hours so that approximately 3,000,000 cubic feet 
of air per hour under these conditions properly ap- 
plied will dry the bricks. 

The expense will be the cost of moving the air with 
a fan and engine, which under a resistance equal to J 
inch of water per square inch ofs urface, is theoretically 
equal to 1 horse-power per million cubic feet of air 
moved, and in practice is about 6 horse-power for 3 mil- 
lion cubic feet. The exhaust steam from this engine and 



DRYING BY AIM CURRENTS. 



289 



from any other source or engines there may be on the 
premises can be used to warm the air as far as it may 
go, but I do not propose to warm the 
air by direct steam from the boiler, as 
almost any air, day or night, is capable 
of taking up some moisture, as every 
one should know by watching clothes 
dry on the line during a freezing day, 
or any day that is not raining or foggy. 
Five grains of moisture per cubic foot 
of air is probably not too high, but 
even if it is, by 50 per cent, twice the 
quantity of air moved will do the same 
work, so that 12 horse-power for mov- 
ing air is a liberal estimate for drying 
60,000 bricks. It is simply acceler- 
ating Nature's method. 

Since that time many persons dry 
bricks Avith force and a little heat, par- 
ticularly stove linings, terra cotta and 
the like. The goods are placed on 
racks in long rows enclosed by shut- 
ters, so the air will be forced length- 
wise over the whole mass. Sometimes, 
where engines are not wanted, aspir- 
ating chimnies are built and the air is 
moved in this way by drawing it. Fig, 
112 shows a method where the fan is 
employed, and Fig. 113 shows the as 
pirating shaft. 

When steam is used coils may be 
placed, as shown, in the racks. AVhen 
the air first enters it has a certain 



Fig. 112. 



290 



STEAM HEATING FOR BUILDINGS. 



capacity for moisture, but of course this becomes 
less as it travels on its way over the wet goods. A 
coil at a raises the temperature of the air, and its power 






09 







^^ 



'-"ry 




DRYING BY AIR GURREITTS, 291 

to take up more moisture is increased. As it becomes 
saturated again, another coil, 5, helps its absorbing 
power again, and this may be carried to a considerable 
extent in drying certain things. It produces a com- 
paratively uniform drying and prevents the necessity 
of changing the positions of the goods. In the case 
of brick or heavy articles that cannot well be moved, 
ducts may be run underground or in any other man- 
ner whereby the air can be diverted so as to blow for 
an hour from one direction and an other hour from 
another direction, or from different directions, modifi- 
cations of which will suggest itself to any inventive 
mind. 

Innumerable are the uses to which modifications of 
this system can be applied. I have used it for drying 
bricks and stove linings and also to dry shoes in cer- 
tain stages of their manufacture. 

In Fig. 113 s is the boiler to make heat in the aspe- 
rating shaft or chimney. 

When it is not desirable, or it is impracticable, to 
use relay coils in such drying rooms, it often happens 
the goods can be stacked on movable racks on wheels 
so that by changing positions evenness in drying can 
be obtained. 

It is well to call attention also to the fact that goods 
dried in a high temperature will appear damp, and 
will be actually damp when removed and allowed to 
cool to the temperature of the outer room. This is 
caused by the great quantity of moisture, warm or hot 
air may contain and still be relatively dry. Airing 
before a hot coil or stove will drive off this residual 
moisture. 



CHAPTEE XXVI. 

STEAM-TEAPS. 

A STEAM-TRAP is an appliance attached to certain 
classes of steam apparatus, whose object is to remove 
the water of condensation without a waste of steam. 
A gravity apparatus does not require a steam-trap of 
any kind ; and a proof of a perfect gravity circulation 
is shown by the proper working of the apparatus with- 
out one. 

Traps may be separated into two principal classes 
— namely, traps which open to the atmosphere or in- 
to a receptacle having less pressure than the heating 
apparatus, and direct return traps, returning the water 
to the boiler, without a considerable loss of heat or 
any loss of water. 

I will speak of the gravity return trap first, though 
they are now almost superseded by pump governing 
apparatus where there is sufficient pressure in the 
boiler to run a pump. 

These direct return or automatic traps came into 

292 



STEAM TRAPS. 293 

use about 187D, and then formed a new departure in 
steam-traps. They must, to be efficient, be automatic 
in action and of simple construction and positive, for 
an interruption of an hour will fill the coils and pipes 
with water, and in very cold weather may be the cause 
of freezing the apparatus, so that caution must be ex- 
ercised in the selection of them. There are now two 
or three very good modifications of this trap before the 
public. 

The principle involved in these traps is simple, 
being alternately a vacuum and a pressure, but, like 
the single acting reciprocating pump which has no fly- 
wheel to help it at the end of the stroke, it must iiave 
some kind of an auxiliary. 

With the aid of the diagram, Fig 114, the action of 
these traps may be explained. A represents ^ the 
boiler ; ^, the trap proper ; 0, the receiver, which 
holds a certain quantity of the return- water ; D, a 
steam pipe from the boiler to the trap ; I^, a pipe from 
the trap to below the water-line in the boiler ; and F, 
a pipe from the receiver to the trap carried up inside 
the globe. It will also be seen these pipes are pro- 
vided with valves ; the steam-pipe has a globe-valve, 
and the other two pipes, check-valves ; the valve in the 
pipe F, opening toward the trap, and the valve in the 
pipe F, opening toward the boiler. 

Now, if the valve in the steam-pipe is opened and 
steam admitted to the globe JB, until all the air is ex. 
pelled and the steam allowed to condense, as it will 
do in a short time after the valve is closed (by the 
loss of heat from the steam through the sides of the 
globe to the outside atmosphere), there will be a vac- 



294 



STEAM HEATING FOR BUILDINGS, 



uum formed in the globe, more or less perfect, which 
will draw water from the receiver C, when there is a 
pressure in the pipe which comes from the coils or 
elsewhere ; and this water, passing the check-valve in 
*F will overflow into B and cannot return to C, for two 
reasons — because it cannot pass the check-valve back- 

D. 




ward and cannot get back over the top of the pipe F. 
Now, if the valve in the steam-pipe is opened and the 
pressure of the steam in the boiler admitted into the 
top of the globe B, the pressure will become equalized 
between the boiler and the globe, and allow the water 
to pass down the pipe E, and into the boiler of its 



STEAM TEAP8. 295 

own gravity (precisely as it would if everything was 
opened to tlie atmosphere), going tlirougli tlie other 
check-valve, which will not allow it to pass back 
again when the valve in the steam-pipe is closed. 
Condensation will again form a vacuum, which will 
once more draw the water from the receiver to flow 
down into the boiler w^hen the steam-valve is again 
opened, and thus the action goes on, being simply 
that of a pumj) without a piston. I say the vacuum 
will draw the water from the lower bulb ; this of course 
is not exactly what goes on. It is the pressure that 
sends it up, and as soon as the trap grows a little old 
and its steam valve leaks, as it always does, it would 
not work at all were it not for the pressure in the 
return pipe. 

This principle was understood and used substan- 
tially as explained above before the automatic traps 
were introduced, but as it was necessary to construct 
the two globes or tanks of large size to avoid too fre- 
quent attendance, and as it required manipulation at 
irregular intervals, which, if neglected, would fill the 
pipes with water, it was not much used. Now, since 
automatic contrivances have been invented, which 
take the place of manipulation, and which can be 
depended on v/ith some degree of certainty, these 
traps can be, and are, used on apparatus which other- 
wise w^ould be almost useless. Thus the difficulty to 
be overcome in this class of traps as before mentioned 
is to construct an automatic contrivance for opening 
and closing the steam-valve, which can be relied on. 

Fig. 115 shows one of these traps, which has been 
selected as an example, not because the trap is con- 
sidered the best— for there are others equally good — 



296 



STEAM HEATING FOR BUILDINGS. 



but because the action of the auxiliary is so easily ex- 
plained. It is a view of the trap when set up ; ZT is 
the steam-pipe ; G, the pipe from the receiver to the 
trap ; and F^ the pipe from the trap to the boiler. 
The valve marked D is the steam-valve, which is autom- 
atically regulated, and is a rotary slide-valve; E, a con- 
necting rod between a crank on the valve stem and an 




arm with slack motion, a part of the casting 0, which 
rocks on the stud ; G, a track, on which rolls a ball, 
also a part of the casting which rocks on the stud 
before mentioned, and which engages another stud, on 
the lever B ; the lever B and its weight are a coun- 
terpoise to a float inside the globe. The action is as 



STEAM TRAPS. 297 

follows : When there has been vacuum in the globe, 
the water will pass through the pipe G, and fill the 
trap, consequently it raises the float and lowers the 
lever and counterpoise, whose stud engaging 0, draws 
it down until the track passes the horizontal position, 
without affecting the connecting rod ]^, on account of 
the lost motion. When the track has passed the hor- 
izontal position, the ball will roll along the track and 
strike on the opposite end against the hook, giving a 
blow sufficient to move the valve on its seat and open 
it to its full extent, but not before the globe is full of 
water. The reverse motion is similar : the float low- 
ering, but not affecting the valve, until the water is 
nearly all out of the globe; the slack motion allowing 
the valve to remain open until the track again passes 
the horizontal position, when the force exerted by the 
blow on the hook at the other end of the track closes 
the valve suddenly. 

Fig. 115a shows a view of one of these traps called 
the ''Bundy/' This trap is sometimes called a pump- 
ing trap, because it can be made to do about what a 
pump will accomplish. The water of condensation 
passes into the bowl through the inlet D. When the 
bowl is filled with water it overcomes the counter- 
balance weight and drops, hfting the valve stem H 
and thus opening the connection from / to the bowl 
through the long upward curved pipe and closing the 
connection from J. The connection 7 is a high pressure 
steam connection, so that steam passing into the bowl 
enters at the top and forces the water in the bowl to 
pass back through the connection D. 

The high-pressure steam pipe is often supplied with 



298 



STEAM HEATING FOR BUILDINGS. 



a reducing pressure valve, so that steam will not rush 
into the trap too violently. The condensed steam inlet 
and outlet connecting to the trap must be provided 
with check valves, so that the water cannot be forced 
back through a pipe through which it has once passed. 
The discharge connection from D should also be pro- 
vided with a resistance valve if there is clanger of steam 
passing directly from the inlet to the outlet connection 




Fig. 115a. 

^t D. When the water has been ejected from the bowl, 
the bowl will fall, closing the valve I and opening the 
connection from the bowl to J. This is called a vent 
connection. It allows the escape of air when the trap 
is first started up and it also acts as an exhaust con- 
nection, when it opens after the trap has been filled 
with live steam. This pipe is sometimes vented to the 
open air, where it will not be a nuisance, but it is better 
if possible to connect it into a low-pressure steam line. 
Among the atmospheric traps are found the old 



STEAM TRAPS. 



299 



expansion traps, now little used, and the open float 
traps, which still form a necessary part of certain 
apparatus. 

Cooking apparatus, such as meat-kettles, or kettles 
or tanks with coils in them, which condense much 
steam in a short time, should not be connected with a 
low pressure gravity apparatus but should have a 
separate pipe from the boiler, and be connected to a 
trap, in consequence of the great and sudden shrink, 
age of steam, which takes place when they are quickly 
filleb with cold water. 

Fig. 116 shows a well known type of open float-traps, 
used both in this country and in England, of which 
there are many modifications of minor importance ; 




Fig. ii6. Fig. ii6a. 

the action and principle remaining the same. A is sl 
cast-iron pot, sufficiently strong to withstand bigh- 
pressune steam, with an inlet ai F ; B is another pot 
(an open pot), inside the pot A, with a spike at the 
center of the bottom and a guide to keep the inner 
pot in a central position. (7 is a brass tube screwed 
into the cover D, and forming a valve with the spike 
at the inside of the bottom of the pot ^/ ^is a valve 
in the cover of pot A, which, when opened, acts as 



300 STEAM HEATING FOR BUILDINGS. 

an air-valve, or blow-through, to quicken the circu- 
lation wlien first turning steam on the spparatus. 

The pot-trap operates thus : the condensed water 
from the coils, etc., runs in at the pipe F and fills the 
outer pot A with water until it floats in the inner pot 
Bj against the stem O, closing the valve formed bj 
the spike and the tube, thus closing the outlet to the 
tank or the sewer. The water, which still continues 
to flow into the outside pot, rises and overflows into 
the inside pot. Then the latter sinks and opens the 
valve which the spike forms with the hollow stem and 
allows all the water in the inner pot to be forced up 
through the stem and out bjthe pressure of the steam 
in the upper part of the pot acting on the surface of 
the water. Thus, when the inner pot becomes buoy- 
ant again, by the discharge of its water, it closes the 
valve and leaves it so, until the increase of the con- 
densed water again overflows it. This action is inter- 
mittent, the frequency of it depending on the amount 
of work to be done. 

There is one point in the construction of this trap on 
which its working depends, namely, the area in square 
inches of the hole in the end of the hollow stem C 
must be no larger than the quotient obtained from 
dividing the weight in pounds of the inner pot when 
submerged, by the maximum pressure in pounds per 
fsquare inch of the steam to be carried. Thus, if the 
inner pot weighs 12J pounds under water, and the 
greater pressure of the steam is to be 100 pounds per 
square inch, the whole must be a little smaller than 
J the area of a square inch, say a round hole J of an 
inch in diameter, which leaves a factor of safety of ■§• 
the weight of the pot. The reason for this is plain 



STEAM TRAPS. 



301 



wlien we consider that there is practically no pressure 
within the stem when the valve is closed, and for the 
pot to sink, when it is full it niust be heavy enough to 
pull itself away from the stem, and still be light 
enough to float with considerable buoyancy when 
empty. 

This type of trap possesses a special point of excel- 
lence ; it will discharge the water of condensation 
from coils or from the cylinder of an engine into a 
tank or sewer at a very much higher level than that 
which drains, and it will keep them as dry as if it djs- 




Fig. 117. 

charged downward. It is peculiarly adapted to ele- 
vator engines and pumps which stop and start fre- 
quently, and are operated from the car or an upper 
floor, as it removes the water at a high temperature 
and will keep a steam chest and cylinders dry by 
removing the water which accumulates while the 
engine or pump is standing with steam turned on. 

The best known modification of this trap is the 
"Mason." Mr. Charles E. Emery, C.E., designed ^a 
modification of this trap which works with a slida 
valve, the object undoubtedly being to get a trap that 
would open under high pressure and give a compara- 



302 STEAM HEATING FOR BUILDINGS. 

tively large opening. Another modification of the xrap 
in which leverage is employed for the same purpose is 
the " Kieley," Fig. 116a. There is another open float 
trap, Fig. 117, which contains a special point of merit^ 
the valve of which is not much understood, namely, 
a trap capable of taking recognition, so to speak, of 
temperature, as well as quantity, and which will 
discharge its water down to atmospheric temperature 
and pressure, no matter what may be the temperature 
of the water in the coils due to high pressure. 

To make this clear, it is necessary to explain that 
pressure, leaving the temperature of the water (when 
water which falls to the bottom side of a nearly hor- 
izontal pipe with 50 pounds pressure of steam in it, 
has not fallen to a temperature of 212° Fahrenheit, 
as is very generally supposed, but has simply parted 
with the latent heat of the steam, incidental to the 
the flow and pressure of the steam are maintained) 
a very little less than the temperature of the steam. 
When this water is exposed to a lower pressure 
some of it will evaporate again, and part of the 
sensible heat of the water will become latent in 
the steam thus formed. But it must not be under- 
stood that all the water flies into steam. It does 
not ; the quantity of water converted into steam 
being represented by the ratio, the latent heat of the 
steam at the different pressures, bears to the sum of 
the latent heat and the sensible heat of steam. Thus, 
when water is drawn directly from a high-pressure 
coil into the receiver of a trap, and is discharged 
against the presence of atmosphere, before the water 
has cooled below 212°, that is a considerable loss of 



STEAM TRAPS. 303 

heat. This can be seen in the blowing of a gauge-cock, 
for though the water is solid and dense in the boiler, 
when it is drawn, some of it flies into steam and makes 
a cloud which often deludes the novice into the belief 
that it is all steam, and that j)ossibly he has low water. 
The construction of this trap is plain ; it consists of an 
outside case with a loose cover, an open float with the 
mouth down, and a common plug-cock operated by 
the float. When steam or water above 212° in tem- 
perature is discharged through the cock and under 
the float, the latter is immediately raised by the pres- 
sure of the vapor underneath and between the float and 
the water which cannot flow over the case. This 
action closes the cock, w^hich will remain closed until 
the vapor condenses and allows the float to once more 
sink, when the cock again discharges the hot water 
behind it. If this water is below, 212°, it will pass 
rapidly out of the case under the edge of the float ; 
but when it again becomes hot enough to make a 
little steam, the float raises and the cock is again shut. 

This trap cannot be used on an engine, as it will not 
discharge any considerable quantity of water until 
the temperature is below 212°; but for an expansion 
system, where the trap has not to discharge against 
pressure, or for an exhaust steam system, it is a good 
one. 

There are many forms of expansion traps or those 
depending on the difference of the expansion of metals 
for their operation. They are difficult of adjustment, 
and are apt to be erratic in action, as they change 
their length with every change in steam pressure. 



304 



STEAM HEATING FOR BUILDINGS. 




Fig. Ti5«. 

Fig'. 115a shows tlie best known form of the type of 
trap shown in Fig. 115. It is the Kieley " Champion " 
and depends for its positive action on a weighted level 
that alternately passes its centre of gravity. 



CHAPTER XXVII. 

VALVES FOR RADIATORS. 

155. It is not necessary that I should say much 
about radiator-valves, as all practical men must be 
conversant with their details. In an early chapter of 
this book, I pointed out the objection to using a globe- 
valve except on its side for any purpose, and in con- 
necting radiators I am not sure but that I should 
take the position that a globe-valve should not be used 
under any circumstances. A suitable straight valve for 
a radiator we have not, as a gate valve is unsuited for 
high pressures. The angle valve, therefore, becomes 
the favorite valve for radiators, and in most cases it 
can be used with the pipes coming through the floors, 
and the steam and handle of the valves uppermost. 
It is, however, of irregular cases that I have to speak, 
and I find that it is often better in matters of this 
kind to warn a person against what should not be 
used, than to say a great deal about what may be used. 
Therefore, I say, never use a globe valve as a radiator 
valve when you can avoid it, and never under any cir- 
cumstances use a globe valve as a radiator valve with 
the stem and handle in the vertical position. 
. 305 



306 



STEAM HEATING FOR BUILDINGS, 



Fig. 118 shows a radiator connected with two globe 
valves and it is only necessary to have a practical man 
study the drawing and discover the mistake that is so 
often made without my referring more to it in detail. 

To those who have had little or no experience with 
heating I will explain that there is practically as 
much pressure in the return end of a radiator, in an 
ordinary system, as there is in the steam end, the two 
globe valves (as shown) will " trap " the base of the 
heater full of water, as represented. When condensa- 








Fig. ii8. 

tion takes place, as it must, within the pipes of the 
radiator, the greater pressure in the pipes will force 
inward at the two ends and nearly alike. This will 
prevent the water accumulated in the base above the 
valve line from flowing out easily, as it should, and will 
make it assume a level still higher than is shown. This 
will make the water rise against the bottom of the 
tubes, and allow it to pass up in the tube the air valve 
is on when the latter is opened by relieving the pres- 
sure in the heater still more. The natural result is 



VALVES FOR BADIATO:^S. 307 

the partial filling of the radiator with water, the accu- 
mulating column of which preponderates against the 
entering steam at the lowest or return end intermit- 
tingly, thus finding its way out of the heater suffi- 
ciently not to let the heater become cold, but accom- 
panied by noise. 

If the valves are turned the conditions are some- 
•fsrhat better, as then the steam has a clear passage, 
though if the globe valve must be used it is better to 
turn them with the stem sidewise, but not quite down 
to the level. This gives a clear and level waterway 
on a vertical section 

When the radiator connections are above the floor, 
the angle valve cannot be used unless the radiators 
have unusually long legs, or are set on supports, both 
of which are objectionable. The ordinary corner valve, 
which is no more than a globe valve with the inlet and 
outlet of the valves at right angles to each other, are 
just as objectionable as the globe valve proper, and in 
fact more so, as they cannot be used on their side as 
the globe valves can, so that this brings us to the use 
of the offset corner valve shown in Figure 119. 

Offset opposite valves are not new, although it is 
only recently that any maker has kept them in stock. 

Lewis Leeds, the ^ventilating engineer, used them 
fully twenty-five years ago, and H. M. Smith, an engi- 
neer of the New York Steam Company, now deceased, 
modeled the offset corner valve after Mr. Leeds' valve 
so as to make a neater and shorter connection without 
the use of a nipple and elbow. His object was to pro- 
vide a corner valve for use when connections to risers 
must be made above the floors, that will admit of the 
running of all the water of condensation from the 



308 



STEAM HEATING FOB BTIILDING8, 



base of a radiator by gravity, and wbicli in tlie ordi* 
nary globe valve is forced to rise to the lieiglit of the 
seat or " bridge " when the stem is in an upright posi- 
tion, as shown in the illustration of the radiator Fig.llS. 
To accomplish this an offset is formed in the body 
,f the globe, which is plainly shown in Fig. 120, and 
qual to a little more than one-half of the diameter of 
tLe pipe. The inlet (when the valve is used as a *' re- 




Fig. 119. 



Fig. 120. 



jurn-valve ") enters highest, and its lowest side is level 
with the top of the seat, over which the water must 
flow to pass into the outlet. When it is used at the 
steam end of a radiator, the lower pipe then becomes 
the inlet, and water formed in the nipple can run 
backward to the riser if it is not carried into the base 
of the radiator. 



VALYBS FOR RADIATORS, 309 

Fig. 119, partly in section, shows tliis arrangement, 
a being the Yalve-disk, c the valve -seat, and the line h 
the level of the top of the seat. 

The offset corner valves are made " right hand " and 
" left hand," so as to be nsed on opposite ends of the 
same radiator, and in general practice the offset valve, 
whether opposite or otherwise, can be used in view of 
globe valves without materially increasing the length 
of the legs of the radiators when they are short, and 
with most ordinary radiators as they are now built, 
wirli the inlets and outlets about four inches from the 
center to floor. 

Fig. 121 shows an iniprovement that may be added to 
any valve that is to be controlled from a distance. Its ap- 
plication to a radiator valve is directly for the purpose of 
controlling the steam in the radiator by the temperature 
of the room, the medium being a metalhc (or other com- 
position; thermostat operating an electric or pneumatic 
circuit, which in turn operates the valve by pneumatic 
pressure. It is called the Thermostatic System, Com- 
pressed air is used as a motive force for opening or clos- 
ing valves which regulate the heat supply. The com- 
pressed air is obtained either by an hydraulic or steam 
compressor, and is stored in an air receiver, and thence 
distributed by suitable pipes to the thermostats, from 
which in turn the air is carried to the valves. 

The steam or hot-water radiator valve has an ordi- 
nary valve body set in the usual manner at the end of 
the radiator, and connected with an expansive dia- 
phragm which serves to open or close the valve. 
This will be better understood by the following sec- 
tional view of the diaphragm valve. 



iio 



STEAM HEATING SOU BUILDINGS. 




Diaphragm Valve. Sectional View of Diaphragm Valve. 

Fig. 121. 

A is the valve body ; B, the valve disc ; C, the pack- 
ing box through which the stem passes ; H is a 
saucer-shaped piece fastened to the upper end of the 
stem D. The valve is held open by the steel spring h, 
which presses upward on the saucer H. Above this 
saucer H is the umbrella-shaped piece J, held by the 
standards cr, a. Upon the under side of the piece J- 
and fastened to its edges to produce an air-tight joint, 
is the flexible diaphragm K, made of cloth and rubber. 
There is an opening through the pipe M into the 
chamber formed between the metal piece J and the 
diaphragm K. When air, under pressure, is admitted 



■^^ 



VALVES FOB RADIATORS. 311 

tlirougli the opening M, the valve will be pu«shed down- 
ward to its seat. When the air is allowed to escape 
from above K, the spring h will open the value B to 
its full extent. 

The passage of the compressed air to the dia- 
phragms on the valves or dampers is controlled by 
thermostats located in the rooms where the tempera- 
ture is to be controlled. 

The thermostat was first made of a compound strip, 
made of brass and steel, and a small double valve. It 
is provided with an index whereby it is set to operate 
at any reasonable temperature, and can be so accurately 
adjusted that it will operate on a variation in tempera- 
ture of one degree. A thermometer used on the face is 
merely for the purpose of showing the temperature and 
testing the accuracy of the regulation. 

The Johnson Service Co., the Powers Regulator Co., 
and the National Regulator Company are the best 
known makers of heat-controlhng apparatus. 



CHAPTEE XXYIII. 

REMARKS ON BOILER CONNECTIONS AND ATTACH- 
MENTS. 

Feed Pipes. — The feed-valve should be a globe or 
angle valve placed near the boiler, with the fewest pos- 
sible joints in the feed-pipe between it and the boiler. 
If it is a loose or swivel disk valve, it should be secured 
with solder (sweated in) in the threads of the double 
part of the disk, so as to make it almost impossible to 
loose the disk from the stem ; a mark with a center 
punch or chisel is not enough. The valve should be 
so turned toward the boiler that the inflowing water 
will be under and against the disk, so that in the case 
of the loss of the disk, it will not act as a check-valve 
against the influx of the feed-water. This arrangement 
will bring the pressure of the water in the boiler al- 
ways against the stuffing-box of the valve ; but all 
things considered it is best. 

The check-valve should be closed to and outside the 
feed-valve, with only a nipple between them. Always 
use horizontal check-valves, as they admit of easy 
cleaning. With the ordinary vertical check it is neces- 

312 



REMARKS ON BOILER CONNECTIONS. 313 

sary to take down some part of the feed-pipe to clean 
it. 

When two or more boilers are fed from the same 
pump, or when the pump is used for pumping water 
for some other purpose, it is well to have a stop-valve 
on each side of the check-valve, as it will enable the 
engineer to get at his check without stopping the 
water elsewhere. 

In passing through boiler walls or cast-iron fronts, 
care should be taken that the feed-pipe does not nest, 
or the settling of the boiler will break it off. 

Use a flange union on the feed-pipe instead of the 
common swivel union. The engineer can take a flange 
union apart with a monkey wrench, and it makes a 
more permanent piece of work than an ordinary union 
and is not likely to leak. 

Never put a T in the feed-pipe inside the feed-valve 
for the purpose of a blow-off; but make a separate 
blow-off connection to the boiler. 

Bloio-off Cocks. — Never use anything but a plug cock 
of the best steam metal throughout or the asbestos 
cock. The reasons for using a cock are, that the engi- 
neer is always sure when he looks at it whether it is 
shut or open. It gives a straight opening. If chips, 
packing, or dirt gets into the cock it will shear them 
off when closing, or if it does not, the engineer knows 
it is not shut. Do not use an iron-body cock with 
brass plug, for when the cock is opened to blow down 
a little, the hot water expands the plug of the cock 
more than the body, and it is almost impossible to 
close it. Do not use a globe or angle-valve, as you 
cannot always tell when it is shut ; a chip or dirt 
getting between the disk and seat will prevent its 



314 STEAM HEATING FOR BUILDINGS. 

closing. I have seen two fine boilers destroyed from 
this cause. Gate or straight-way valves are subject 
to the same objections as globe or angle types. 

When it is practicable there should be a T with a 
plug in it in the blow-off pipe outside the blow-off 
cock, and the plug so arranged as to be removed when 
the cock is closed. By this means the engineer can 
always tell if he is losing water from his boiler through 
the blow-off, and in the matter of expert trials it will 
not be necessary to remove a section of the blow-off 
pipe, as the engineer can satisfy himself through this 
hole as to whether there is a loss from the boiler or 
not. 

The blow-off pipe should be large, with few bends 
in it, and fire bends are better than elbows. It should 
be attached to the bottom of the shell of a horizontal 
boiler, and not tapped into the head a few inches up. 
When there is a mud-pipe, attach it at the opposite 
end from the feed-pipe. 

Safety- Valves. — They are the main-stay of the en- 
gineer, acting both as a relief and a warning signal. 
They should be attached to the steam dome high up. 
The side is better than the top, as they are not so 
liable to draw water when blowing off in that position. 
They should be large, and have a large pipe connection 
all to themselves if possible. The ordinary cross-body 
salfety valve, when used as such, is very much to be 
condemned, and I think in some countries there are 
regulations against their use. They are constructed 
to save making an extra connection for the main steam 
pipe, thereby drawing the largest amount of steam 
directly from under the disk of the safety-valve. A 
weighted safety-valve is better than a spring-valve 



REMABKS OH BOILER CONNECTIONS. 315 

when it can be used, as the lifting of the valve makes 
practically no difference in the leverage ; not so with 
a spring-valve, for the higher it is lifted the more 
power it takes to compress the spring. 

Gauge or Try 6bcA;s. — Gauge-cocks are various in 
style, the wood handle compression gauge-cock is a 
very good kind for all purposes. When setting gauge 
cocks care should be taken that they are not too low, 
and that the drip will not flow over the person who 
tries them. They should be tapped directly into the 
boiler if possible ; but when it is necessary to use a 
piece of pipe to bring them through a boiler front or 
brick work, give the pipe an inclination backward, that 
the condensation may run back and into the boiler. 
When the pipe inclines outward and down, the con- 
densation remains in it and the cock, and will deceive 
the unwary, giving the appearance of plenty of water 
with a short blow. 

Glass TFa^er-^^az^^e^. — Water-gauges are best set 
when attached to a vertical cylinder at the front of the 
boiler. The cylinder should be connected to the boiler 
with not less than 1-inch pipe, top and bottom ; the 
top or steam connection should be taken from the 
boiler shell near the front head, and not from the 
dome or steam-pipe, as the draught of steam in either 
will cause the glass to show more water than the boiler 
contains. The bottom or water connection should be 
taken from the front head at a point where about two- 
thirds of the water in the boiler will be above it and 
one-third below ; this will lessen the chances of the 
pipe stopping up with mud, etc., and it should also be 
provided with a half inch pipe at the lowest point for 
a blow out. When gauge glasses are set this way the 



316 STEAM BEATING FOB BUiLDINGS. 

condensation in tlie cylinder is downward, and the flow 
of water being toward the boiler through the bottom 
pipe, the tendency is to clean the glass and cylinder 
and keep them so. 

Steain Gauges should never be set much above or 
below the boilers to which they are attached, as each 
27 inches of fall or elevation from the direct connec- 
tion is nearly equal to a difference of one pound on the 
steam-gauge. It is always so when the gauge is below 
the point of attachment, for the condensation in the 
gauge-pipe fills it with water, which leaves a pressure 
on the steam-gauge equal to the hydrostatic head, 
which is a little over two feet perpendicularly to the 
pound per steam-gauge, giving the gauge the appear- 
ance of being weak. When the gauge is above it is 
not so always, though generally so even then, for the 
pipes being long and of small diameter, or trapped, 
which prevents a circulation of steam in them, they 
fill with water, which acts against the pressure from 
the boiler and gives a gauge the appearance of being 
strong. 

When it is necessary to have a gauge very much 
lower than a boiler, fill the pipe with water, but before 
doing so remove the glass and lift the hand or index 
over the stop-pin and mark where it remains station- 
ary. Now fill the pipe to its highest point with water, 
then draw the index hand from its spindle and set it 
back to the mark where it remained stationary before 
the pipe was filled, and press it on ; then bring it to 
its normal position on the stop-pin and adjust the 
glass. 

The Main Steam-Pipe for Heating Apparatus should 
be high up on a boiler, and any pipe larger than 2 



REMARKS ON BOILER CONNECTIONS. 317 

inch should not be tapped in, but connected with a 
flange bolted or riveted to the boiler. Two-and-a-half 
inch pipe and larger sizes have eight threads to the 
inch, which forms too coarse a pitch to be tapped 
into one thickness of boiler-iron. 

Automatic water-feeders, combination water-gauges, 
or steam-gauges, should not be ta]Dped into the steam- 
heating or engine pipe, as the draught of the steam 
through the pipe interferes with their proper working. 

Engine or pump pipes should not be taken from the 
steam heating pipe of a gravity apparatus, as the 
draught they cause relieves the pressure in the heat- 
ing apparatus to a considerable extent. 

All pipes connecting with boilers should be extra 
thick until at least the first cock or valve is reached, as 
much of the pipe now on the market is below the old 
Morris Tasker Co. standard, and is too thin, 1 inch to 
2 inch inclusive being the sizes which give the most 
trouble. 



CHAPTEE XXIX. 

DATA ON CONDENSATION IN RADIATORS. 

Me. Thomas Teedgold, early in the present century, 
considered the question of loss of heating and radiat- 
ing surfaces in a very thorough manner, and later he 
was followed by Mr. Charles Hood on the same sub- 
ject, both having the same object in view — namely, to 
find the value of radiating surfaces for warming build, 
ings. 

Mr. Tredgold found that 2.19 pounds of water cooled 
from 180° to 150° Falir. in a vertical tin cylinder in 
46 minutes, the exposed sides of which were 79 square 
inches, when the temperature of the room was main, 
tained at 55J-° Eahr. during the trial. This gave a 
mean difference between the air of the room and the 
surface of the cylinder of 109.5° Fahr. 

From this we have 2.19 pounds of water cooled 30° 
Fahr. by -^^ of a square foot of surface in 46 minutes of 
time, which is equivalent to 65.7 heat-units for the 
time, or 85.7 heat-units for an hour of time, and 156.21 
heat-units as the quantity what would be given off by 
one entire square foot of the same surface (tin cylin- 
der) in an hour of time. This total heat, for a square 

318 



DATA OF CONDENSATION IN RADIATORS. 319 

foot of surface, for an hour of time, then, divided hy 
the mean difference of temperature (109.5 Falir.) be- 
tween the air and the surface of the cylinder equals 
1.42 heat-units ; the amount given off per square foot 
of surface per degree difference of temperature. 

His second experiment was with a glass cylinder 
that held 2.125 pounds of water and had a surface of 
71 square inches. It cooled from 180° to 150° Fahr. 
in 31|- minutes in a temperature of 56|-° Fahr., which, 
by the same method of reasoning as we used before^ 
gives 2.248 heat-units per hour per square foot of sur- 
face per degree (Fahr.) difference of temperature. 

His third experiment was with a sheet-iron cylinder 
the surface being that of new sheet-iron unpainted 
whose surface was 76.7 square inches, holding 2.14 
pounds of water and cooled from 180° to 150° Fahr. in 
29 minutes, the temperature of the air of the room 
being 57° Fahr. By the same reasoning and method 
of calculation used in the foregoing examples we can 
find that the sheet-iron gave off 2.35 heat-units per 
hour per square foot of surface per degree difference 
of temperature. 

These cylinders were as nearly alike as they could 
be obtained in form and size, and one cover fitted alL 
They were suspended by cotton threads, so that little 
or no heat could be lost by conduction or contact, and 
the sides and bottoms were exposed to the action of 
the air, etc. The top was covered by about one inch 
in thickness of alternative folds of cotton and flannel, 
so that the loss of heat by this direction was very 
small. 

A few days later, when the experiments were re- 
peated, the iron cylinder had become rusted. This 



320 STEAM HEATING FOR BUILDINGS. 

Mr. Tredgold says, increased its efficiency in the pro 
portion of 156 and 180 ; the rusted cylinder having 
having the latter value, when as a new one it had the 
former. The experiments with the tin are of no value 
to us, except to show that bright surfaces have a less 
value than dull or slightly roughened ones. Experi- 
ments with brass, etc., by other experimenters confirm 
this. The relative value of glass and iron, however, 
are of some value to us as showing how nearly they 
agree ; the iron being the better of the two, even when 
new and bright, and increasing in value as it becomes 
rusty. 

It would be well to remark here that, probably, when 
surfaces become rusty, which they will in practical 
heating, they may deteriorate somewhat, and that it 
would be well to assume what they may increase in 
efficiency by rusting will be fully offset by accumula- 
tions of dust, etc. 

The form of Mr. Tredgold's cylinders (short, vertical 
ones) are presumbly the best that can be devised for 
giving off heat. The same cylinders in a horizontal 
position would probably be found to be a little less 
efficient, and if they were to be increased in height, 
say two or three times, though used in a vertical 
position, it is only reasonable to suppose they would 
do less duty, for the very simple reason that the air in 
contact with the upper parts would have been warmed 
somewhat by the lower part as it passes upward, 
and, therefore, is not capable of extracting as much 
heat. The same holds good of horizontal pipes or 
cylinders when placed one above the other ; each 
successive one, counting from the bottom upward, 
does less work than the one next below it. 



DATA OF CO HfBENSATIOIf^ m BADIATOBS. 321 

According to the above relative values, therefore, of 
glass and iron, the empirical rule given before for 
finding heating surfaces by the window area, etc., is 
not without some scientific pretence, as the loss of 
heat through the glass of a window can rarely, if at 
all, be greater than through the iron of the heaters 
for equal difference in temperature, or for proportional 
differences.* 

To go further with this subject, I will refer to ex- 
periments of Mr. Hood made more recently than Mr. 
Tredgold's, as he was not satisfied with the latter's 
deductions, and made experiments for himself. In 
his work on " Warming and Ventilation " he tells us 
that " to asertain the velocity of cooling for a surface 
of cast-iron, a pipe 30 inches long and 2|- inches 
internal diameter, and three inches diameter exter- 
nally, was used. The ends of the pipe were closed by 
corks, which entered the pipe 1^ inches at each end, 
and the bulb of the thermometer was inserted into 
the water about three inches from the end. The 
exposed surface of the pipe (including the surface ex- 
posed by the thickness of the metal at the ends) was 
287.177 square inches. The quantity of water con- 
tained in it w^as 132.534 cubic inches, and the equiva- 
lent to be added for the specific heat of the pipe was 
39.341 cubic inches, making the estimated quantity of 
water 171.875 cubic inches." The tem]3erature of the 
room in which the observations were conducted was 
67° Eahr. 

* I do not draw the same deductions from Mr. Tredgold's experiments 
that he does himself, and therefore did not give his figures here, but sub- 
stituted my own in the manner just shown ; the summary of the matter 
being that the heat lost through glass would be 2.248 heat-units, when 
that lost through iron would be 2.35 heat-units. 



322 STEAM HEATING FOR BUILDINGS. 

This pipe was presumably used on its sides in the 
horizontal position (though this is not stated), and 
represented no doubt a section of an ordinary 3-inch 
cast-iron heating-pipe, used at that time for green 
honse heating, etc. 

He informs us the rates of cooling were tried in dif- 
ferent states of the surface. First, when ii: the usual 
state of cast-iron pipes covered with protoxide of iron 
(fine rust) ; second, black varnished ; and third, with 
the varnish removed and two coats of white-lead paint 
substituted. He observed that the rusty surface 
cooled from 152° to 150° Fahr., or 2 degrees, in 2.5 
minutes, and that it cooled from 150° to 140° Fahr., 
or 12 degrees, in fifteen minutes. This is at the rate 
of the whole quantity of water, or its equivalent, cool- 
ing one degree in 1.25 minutes. 

He took observations every two degrees fall of the 
thermometer, which give slightly varying results as to 
the rate of cooling. This variation may be due to 
errors in reading the scales, or in errors in the ther- 
mometers, and a close study of the table of his exper- 
iments go to confirm the belief that for all practical 
purposes of house-warming the rate of cooling is very 
nearly directly as the temperature between pipe or 
or plate surface and the surrounding air. With the 
black surface of the pipe black-varnished, he found 
that to cool from 152° to 140° Fahr. (12 degrees) it 
took 14.533 minutes ; or, in other words, cooled an 
average of one degree in 1.21 minutes, his readings 
showing a slight increase of cooling as the difference 
between surface and air became less. If we take the 
average of six experiments (1.23 minutes), progressing 
by two degrees, and correct the time observed on 



DATA OF CONDENSATION IN .RADIATORS. 323 

cooling tlie first two degrees bj it, we have 2.42 min- 
utes, instead of 2.266 minutes. This shows that the 
black-varnished surface is slightly more efficient than 
the rusty one — a little over three per cent.* 

With the pipe with two coats of white-lead paint, 
the efficiencj^ was less than with either of the others, 
but not as great as usually considered. 

The cylinder cooled from 152° to 150° Fahr. (2 de- 
grees) in (observed time) 2.316 minutes, and it cooled 
to 140° Fahr., or 12 degrees, in 15.366 minutes ; or, in 
other words it cooled one degree in 1.28 minutes 
average. 

Mr. Hood's summary of the matter is that 100 feet 
of varnished pipe, 103^ feet of plain pipe and 105f 
feet of white-23ainted pipe have the same value 
as heating surfaces. He does not, however, give 
us the value of these surfaces in heat-units per 
square foot per degree difference, no more than Mr. 
Tredgold does, and as it is important, w^e shall have 
to calculate it for ourselves by the same method of 
reasoning, etc., as we did in the case of the latter's 
experiments. 

The surface of the experimental piece of pipe is 
given as 287.177 square inches, which is two square 
feet, lacking less than one square inch, and there- 
fore we will call it two square feet. The quantity of 
water actually contained in it was 132.534 cubic inches, 
and the equivalent in cubic inches of water that was to 
be added for the specific heat of the iron of the pipe, 
39.341 cubic inches, making the 6«timated value of 

* In comparing these statements with Mr. Hood's table, note that tha 
time here is given in minutes and decimals of a minute, while in the tabU 
it is given in minutes and seconds. 



324 STEAM HEATING FOR BUILDINOS. 

the water and its envelope equal to 171.875 inches of 
water. 

The water was cooled from 152° to 140° Fahr. in each 
experiment, and therefore had a mean temperature of 
146° Fahr. The weight of a cubic inch of water at 
temperature is 248 grains ; therefore we have 

171.875 cub. in. X 2 48 grs. , 

. w-Fu^ .-, in X — = 6.089 lbs. of water. 

7,000 grs. (1 lb.) 

This water was cooled 12 degrees in the various 
times, which gives us 6.089 X 12 = 73.068 heat-units as 
the total heat given off in each from two square feet 
of heating surface, or 37.534 heat-units per square 
foot. 

The air of the room was 67° Fahr., consequently the 
difference of temperature, or, in other words, the excess 
of the temperature of the surface over the air, was 89 
degrees. 

The time for cooling the rusty cylinder was 15 min- 
utes, or one quarter of an hour ; therefore we have 
36.534X4 
89° Fahr. ^ ^'^^^ heat-units 

per square foot per hour per degree difference. For 
the varnished surface it is 1.589 heat-units, and for the 
white-painted surface 1.552 heat-units. 

To ascertain the effect of glass windows to cool the 
air of a room, Mr. Hood made experiments with a 
glass vessel as nearly as possible of the same thick- 
ness as ordinary window-glass. The temperature of 
the room was 65° Fahr., and the surface of the vessel 
was 34.296 square inches, and it contained 9.794 cubic 
inches of water, including the equivalent for the spe- 
cific heat of glass. He does not tell us the form of the 
vessel, which would be very important to know, but 



DATA OF CONDENSATION^ IN RADIATORS. 325 

presumbly, it was rectangular, or at least had perpen- 
dicular sides, and being small, represented an average 
effect in cooling, so that the deductions obtained are, 
presumbly, fully equal to average conditions. 

The average rate of cooling from 150° to 110° Fahr. 
was found to be 1.176 degrees when the mean excess 
of temperature of surface was Q6° Fahr. above the tem- 
perature of the air, and the time 34 minutes. 

The total quantity of water, or its equivalent, is 
found to weigh .3482 pounds at a temperature of 130° 
(its mean temperature). This cooled 40° Fahr.^ 13.93 
heat-units for 34.296 square inches, or 58.48 heat-units 
for a square foot for 34 minutes, or 103.2 heat-units 
for an hour, divided by the mean difference in tem- 
perature = —p^ ~ 1.59 heat-units per square foot per 

hour per degree difference of temperature. 

Mr. Hood's deductions from his experiment is to 
the effect that each square foot of window-glass will 
cool in a minute of the time 1.279 cubic feet of air 
as many degrees as the inside air is warmer than the 
external in a comparatively still atmosphere, but that 
whem windows are exposed to the action of winds 
further experiments are necessary. 

It is evident the cooling of air through glass, etc., 
depends on both the velocity of the air inside and 
outside taken together. 

Nearly all the heat that is lost by air of rooms to 
cooler air through glass is lost by convection. The 
air inside the glass falls by loss of heat and increase 
of weight and follows the laws of a falling body. The 
velocity of air outside is due to wind-pressure and the 
angle at which it strikes the glass. Quadrupling the 



326 STEAM HEATINQ FOB BUILDINGS. 

velocity of the outer air, however, does not quadruple 
the loss of heat through the glass, for the reason that 
the air inside will not fall in the same ratio, but in a 
ratio about as the square root of the increase of outside 
velocity, so that the loss of heat through glass cannot 
be accurately established for a given difference of 
temperature and a certain velocity of the wind out- 
side. An approximation, however, can be made to the 
loss of heat for other velocities and temperatures. 
Unfortunately, we have no very accurate data on the 
cooling effect of windows for the guidance of heating 
engineers, though on the warming effect of radiator 
surfaces there is not such a scarcity of information. 
Mr. George H. Barrus, of Boston, in experiments 
with a Walworth vertical wrought-iron pipe radiator 
for steam, found that under average conditions of use, 
with eight pounds of steam, in an atmosphere of about 
51° Fah., that the units of heat given off per actual 
square foot of surface was 394.4. If we assume the 
surface of the iron to be 235° Fahr. (the temperature 
of the steam) we have 235°- 51°= 184° difference. 
Then 

r^Toio = 2.143 heat-units. 

This is somewhat less than Mr. Tredgold's experi- 
ments give for a short vertical cylinder, but it is what 
would be expected, as the pipes used were 30 inches 
long, and in a cluster, 2^ inches between centres, 
screwed into a base. 

\Ee also experimented with a Nason radiator of or- 
dinary height, two pipes wide by 24 pipes long. 

Tlie total number of heat-units per square foot of 
surface given off was 347.6, the pressure lof the steam 



DATA OF CONDENSATION IN RADIATORS. 327 

was eight pounds, and the temperature of the air of 

the room 64° Fahr. Assuming the temperature of 

the pipe to surface is 230° Fahr., and the difference 

then between air and heating surface is 170° Fahr. 

, . - . 347.6 heat-units r> /^iK i 
which gives us vnY" ~ i.045 heat-units per 

hour per square foot per degree difference. 

Mr. Barrus' method of measuring the heat was to 
receive the water of condensation carefully and to 
asertain its weight, then compute the heat according 
to the latent heat of steam. The nearness of the 
results thus obtained by vertical radiators of different 
makes, and at different times in different buildings, 
by the same methods, adds value to the data and 
establishes the fact, when taken with other investi- 
gations, that a tube of vertical radiator will give off 
heat equal to about tivo heat-units per square foot per 
hour per degree difference. 

An experiment made by the writer in 1884 on a 2 X 7 
Bundy steam-radiator, for his own information, and 
before the Bundy patterns were altered, to have an 
actual surface equal to 'their commercial rating, gave 
the following results : 

Actual surface, 38 square feet ; water condensed for 
one hour was 12.843 pounds, when the pressure of 
steam was maintained between 1 and IJ- pounds ; tem- 
perature of air of room at floor commencement of 
experiment 52° ; at 5 feet high on side wall 58° ; tem- 
perature of air of room at floor at end of experiment 
57|-° ; and at 5 feet 64°. The temperature of the air 
as it was found at the floor was, presumably, the 
temperature at which it first caroe in contact with the 
heater, but, as in other cases, the temperature of the 



328 STEAM HEATING FOR BUILDINGS. 

room only was noted without informing us further, we 
will in this case take the mean of the temperature 
given, which is 57.9° Fahr., and, presumably, near 
enough for our purpose, which is not to compare 
rival heaters, but to establish the condensation or 
cooling for ordinary conditions of use. 

Taking the temperature of the steam (one pound), 
therefore, at 215° Fahr., and the latent heat of its 
vaporization at 962 heat-units per j)ound, we will have 
— difference of temperature between steam (or pipe) 
157.1° Fahr., and total heat of 12.843 pounds of steam, 
12.355 heat-units, or 325.1 heat-units per actual square 
foot of surface, equaling 2.07 heat-units per square 
foot of surface per hour per degree of difference 
between steam and air. 

It is possible that should these radiators be trans- 
posed as to the buildings they are tested in, the re- 
sults would slightly differ, as the effect of the passage 
of heat by radiation alone from or to the radiator can- 
not be estimated, as it will depend on the surround- 
ing walls, etc. For instance, one experiment being 
made in a cellar and another on the upper floor of a 
building, it is reasonable to assume the localities will 
effect results, and the question of humidity may also 
come in as a factor for or against a radiator. 
Draughts of air, also, Avill materially alter results, 
and the effect of an open hatchway, machinery in 
motion, or down draughts from windows, etc., will all 
tend to throw some uncertainty into the matter, so 
that unless positions, etc., are transposed and the 
water of condensation measured in the same manner 
and with similar apparatus, it would be difficult to 
determine positively which of the above radiators 



DATA OF CONDENSATION IN RADIATORS. 329 

gives the highest result per actual square foot of sur- 
face. Such remarkable uniformity, however, by clif- 
ferent makers appears to establish beyond a doubt 
that 2° Fahr. per square foot of surface per degree 
difference of temperature between the surface and air 
may be taken as the basis of loss of heat from vertical 
radiators, whether they are for hot water or steam. 

This, of course, is the maximum, and it is for radi- 
ators of plain, smooth surface, say not over three feet 
in height, that are not covered up with screens or 
slabs, but used in the most practical manner and not 
too close to the walls. It should be borne in mind, 
also, that these radiators were only two pipes wide, 
and represented slightly more than the average, and 
that radiators of three or four pipes in width should 
not be expected to give quite as good results as radi- 
ators of one or two rows, other things being the 
same. 

It is very possible, taking all the styles and kinds 
of radiators and coils known to the writer, that the 
minimum condensation or cooling may be placed at 
1.25 heat-units and the maximum at 2 heat-units. 
Between these points it must be left to the judgment 
and experience of the fitter to select when the charac- 
ter of the radiator or coil is known. 

There are certain extended surface direct radiators 
that will not give more than 1.25 heat-units; while 
long coils on the walls of, say, one-inch pipe, and not 
too high — say six pipes high — will probably run up 
to 2.25 heat-units. 

Professors Denton and Jacobus, of the Stevens In- 
stitute of Technology, found that an extended surface 
vertical sectional radiator gave 0.0017 pounds of con- 



330 STEAM HEATING FOR BUILDINGS. 

densation per degree difference of temperature per 
hour per square foot of average surface, with steam 
at 3.9 pounds pressure ; which is approximately 1.63 
heat-units, while the same radiator gave 0.00204 pounds 
of condensation per actual remaining square foot of 
surface, the extended surface having been planed off, 
which is approximately 1.95 heat-units. This confirms 
my opinions given many years ago in the earlier 
editions of this book. It does not mean, however, that 
the radiator, as a whole, did more work. It simply 
means that a unit of the remaining surface was about 
20 per cent, more efficient, and that generally an 
equal amount of iron in a plain direct radiator is very 
much more efficient than in an extended surface 
radiator. 

I wish, also, to add that I am not convinced of the 
general "inferiority of extended surface radiators for 
indirect work. The value unit for unit of surface, as 
between extended and plain surface indirect radiators, 
I will admit, is in favor of the plain surface ; but when 
it comes to a matter of dollars and cents, or pounds 
weight of iron used, I believe the extended surface 
inditect radiator to be the most economical. This 
comes from the inability to arrange round iron pipes 
or flat surfaces so that the air passages will be properly 
proportioned to the least amount of surface used, to 
get the required results. In other words, the cast- 
iron extended surface can be arranged so that the air 
can be brought in more intimate contact with it. 

Returning again to condensation in direct radiators, 
the writer here introduces the results of some of his 
own experiments made with cast-iron sectional radi- 
ators. The results do not show as high a rate of con- 



DATA OF CONDENSATTON IN RADIAT0B8. . 331 

densation as those given previously ; but this may be 
chiefly attributed to the fact that the experiments were 
made in cotton-covered boxes or frames, with only six 
inches of space between the sides of the radiators and 
the cotton-covered frames. Top and bottom they were 
open, but in these confined spaces they could not do 
the work they would in a large room under conditions 
similar to their constant use. For comparison, how- 
ever, they were probably all that could be required. 
I may add here that under conditions said to be about 
equal to those of actual use, Professors Denton 
and Jacobus have reported condensation equal to 
2.4 heat-units for one type of direct radiator, but 
which forms entirely too high an average for ordinary 
use. 

The following I take from a paper I contributed to 
the American Society of Civil Engineers, read at the 
June convention of 1894 ; and I introduce it here more 
to confirm the fact that the line of difference of tem- 
perature between the radiator surface and that of the 
temperature of the air of the room agrees very nearly 
with the condensation line in a good radiator — so near, 
in fact, as to be practically the same. 

The writer had occasion recently, in connection with 
his professional work, to make some comparisons as 
to the relative efficiencies of several of the regular 
makes of sectional cast-iron radiators now on the 
market, and ones that are considered good types of 
direct cast-iron radiators. The results of the experi- 
ments hereafter given were obtained from four of 
these radiators that were selected as a standard of 
comparison for a new radiator about to be put on the 
market. The results of these experiments are given 



332 STEAM HEATING FOR BUILDINGS. 

to this Society, as they form valuable data by which 
an engineer can approximate the amount of condensa- 
tion likely to take place in the heating apparatus of a 
buildiug, and also show how near the line of condensa- 
tion agrees in steam pipes with a line of the difference 
of temperature between air and steam. 

The writer is compelled to omit the name and make 
of these four types, but as the results run so nearly 
together he presumes it is not necessary to go further 
than to say that they are the ordinary well-known 
types of cast-iron sectional radiators that are so much 
used at the present day. All radiators were of 48 sq. 
ft. of surface,, according to their commercial rating, 
excepting that designated as No. 3, which contains 
52 sq. ft., and which, when reduced to the value of 
48 sq. ft., gives the dotted line shown and designated 
as X—X, (Diagram Fig. 122). 

The method of comparison used was that known as 
the condensation test, the only one which is of any 
value in determining the comparative value of radia 
tors, and consisted of taking steam from a boiler at 90 
lbs. pressure and conveying it in a 1-in. pipe to a water 
separator. This water separator was " trapped " in 
the usual manner with a Nason trap. From the top of 
the separator a 1-in. pipe led to a reducing pressure 
regulating valve, and from the pressure regulating valve 
it led into a header of 2 ins. inside diameter. The con- 
nection for each radiator was made of f-in. pipe, taken 
from the upper side of this header through a short 
nipple, and thence by another short nipple into the 
radiator, an angle valve being used at the corner. It 
is probable that the condensation taking place in the 
two short nipples and in the valve was carried forward 



DATA OF CONDENSATION IN 'KADIATOBS. 333 



I t^iJCi M t*> en 0» ^ 



STEAM PRESSURE IN POUNDS PER SQUARE INCH 



^^^_ ^ .MT r.NE POUND OF CONDENSE D STEAM-WATER^ 



IN BR-HEAT-UNITS 




Diagram, Fig. 122. 



334 8TEAM KEATING FOR BUILDINOS, 

into the radiator ; but, the quantity being so small, it 
has not been considered, as it was the same in each 
case. 

The radiators were placed on platforms 2 ft. above 
the floor and 36 ins. from center to center. Over each 
radiator was placed a frame covered with muslin. The 
muslin in all cases was 6 ins. from the sides and ends 
of the radiators, and the frames were opened top and 
bottom. The frames had the same perpendicular 
height as the radiator, and were raised sufficiently 
(about 6 ins.) to permit an uninterrupted flow of air to 
the radiator underneath the lower edge of the frame. 
This method enclosed each radiator in a cotton box, as 
it were, and interposed two thicknesses of muslin be- 
tween opposing sides of radiators, so as to cut off al- 
most entirely the effects of radiation from one radiator 
to another. The tables on which the radiators were 
set had an inclination of about 1 in. to the drip end, so 
that the condensation could easily gravitate to the ap- 
paratus for collecting the water. 

The apparatus for collecting and measuring the 
water consisted of a f-in. "tail pipe," on the side of 
which was a short ordinary water-gauge glass. Both 
above and below the water glass in the tail pipe was a 
stop valve, the upjDer valve being for the purpose of 
shutting off the connection should the gauge glass 
break ; but during the experiments it was always open. 
The lower valve was simply a tail valve, to control the 
escape of water. The tail valve was supplied with 1 ft. 
of very light rubber hose (f in.) which terminated in a 
paper pail. The water was drawn into the paper pail 
through the tail valve, but was always kept in sight in 
the glass and made to agree with a thread around the 



DATA OF GOJSBENSATION IN RADIATORS. 335 

middle of the glass, both at the commencement and the 
end of all trials. 

On the header before mentioned was arranged a 
steam-pressure gauge, and in an oil well in the upper 
side of the same header was fixed a standard ther- 
mometer for the purpose of checking errors in the 
steam-pressure gauge by comparisons with the tem 
perature of the steam. It will be noted that the trials 
were generally made at 1, 5, 10, 18 and 30 lbs. press- 
ures, but that some of the circles indicating trials are 
on other lines, notably in the neighborhood of 5 and 
10 lbs. Where the greater number of trials are shown 
these differences of pressure are the results of correc- 
tions made by the thermometer, the pressure gauge 
being somewhat inaccurate and the pressures likely to 
fluctuate -I lb., or thereabouts, as a pressure-regulating 
valve is only an approximate instrument for work of 
this kind. At the lower pressures (1 to 5 lbs.) there is 
very little loss due to the evaporation of the hot water 
as it falls into the pails, especially as the end of the 
hose is kept under water as much as possible. At the 
higher trials a small percentage of the hot water, 
when relieved of its pressure, is converted into steam. 
This is obviated in a great measure, however, by 
keeping the end of the hose always under water, 
which can be done as soon as condensation forms in 
the bottom of the pail and covers the mouth of the 
hose. 

It is well to remark here that the header before 
spoken of, and in which steam at reduced pressures 
was admitted to the radiators, was also drained and 
kept dry by an automatic steam trap. The positions 
of the radiators were also changed from time to time, 



336 STEAM HBAimO FOB BUILDINGS. 

as it was feared that a radiator in one position might 
be favored. 

At the left of the diagram is shown the steam pres- 
sure in pounds per square inch, at which various trials 
were made. 

The next line, A — A, gives the value in British heat- 
units of each pound weight of steam for the various 
pressures, and is measured from the left-hand side 
of the diagram, each of the larger squares having 
a value of 100 heat-units, the thermal value of a 
pound weight of steam being less from the higher 
pressures. 

The curved line B — B shows the results obtained in 
the radiator designated as No. 1, and they were made 
under conditions of very nearly equal temperature, in 
73° and 74° Fahr. 

Line C — G shows results obtained for radiator 
marked No. 6 in the trials, which were made at the 
same pressures and the same temperatures as the fore- 
going. 

Line D — D gives the curve of condensation in the 
radiator marked No. 3, temperatures and pressures of 
steam being the same as before. 

Line E—E shows the results of experiments on 
radiator No. 4, which at the lower temperatures seems 
not to do so well. Between the 10-lb. and 18-lb. lines, 
however, the curve agrees with the remaining curves 
of condensation. 

Line F — ^i^ shows the other experiments made with 
radiator No. 3, when the temperature of the room 
averaged 77° and 78°. This high temperature of the 
room undoubtedly accounts for the line showing less 



DATA OF GONDENSATION m RADIATORS. 337 

condensation on that day. The circles 6, 1 and 3 on 
the 5-lb. line are also results of the tests made when 
the temperature of the room was about 78°. Other cir- 
cles, enclosing figures in close proximity to lines, with 
corresponding figures, show values obtained with the 
same radiator during other trials and under slightly 
different conditions of the temperature and humidity. 
They all harmonize, however, with the curves of 
their respective radiators and tend to confirm the 
results. 

Line G — G is the curve of difference of temperature 
between the steam and the air, and is drawn for com- 
parison with the curves of condensation as discovered 
by the trials. The uniformity that exists is remark- 
able. There is a correction, however, to be made for 
the higher temperatures in the matter of the curves of 
condensation. As the temperature of the steam ad- 
vances, the value of 1 lb. of condensation becomes less, 
as shown in the line A — A, so that curves of efficiency 
of condensation, based on the actual amount of heat 
lost from the radiator, and not from the number of 
pounds of water condensed, would all tend a little to 
the left as they go upward, bending away from the 
curve of difference of temperature. It is well known 
that the condensation does not increase directly as the 
difference of temperature. These experiments, how- 
ever, show that it (the difference) is not as great as was 
surmised, and that for all practical purposes the curve 
of condensation and the curve of difference of tempera- 
ture is practically alike for any ranges of temperature 
and pressures carried in low-pressure steam-heating 
apparatus. 

Since the foregoing paper was written, I have had 



338 



STEAM HEATING FOR BUILDINGS. 



time to have an assistant tabulate the results of the 
experiments given above, which are as follows : 

TABLE. 

AVERAGE OF RESULTS OBTAINED WITH 3 RADIATORS OP 48 SQ. FT. 

EACH. 



1 

\i 

Is 

il 

©CQ 




% 
IS 


M 

a 

I 

is 


L 

iJ 


11 
ill 


ifferenee of Temp, 
in Degrees Fahr. 
between Steam and 
Air. 


nits of Heat per Sq. 
Ft. per Hour per 
One Degree Differ- 
ence of Tempera- 
ture. 


CO 


02 


a 


H 


m 


P 


« 


P 


1 


12 


962 


11544 


48 sq. ft. 


240.5 


141.5 


1.70 


5 


13 


953 


12389 


48 " 


258.1 


153.5 


1.68 


10 


14.4 


945 


13608 


48 " 


283.5 


165.5 


1.71 


15 


15.5 


938 


14539 


48 " 


302.9 


176.5 


1.71 


20 


16.3 


932 


15191.6 


48 " 


316.5 


185.5 


1.70 


25 


17.1 


926 


15834.6 


48 " 


329.9 


194.0 


1.70 


30 


17.8 


921 


16393.8 


48 " 


341.5 


200.5 


1.70 


I. 


11. 


III. 


IV. 


V. 


VI. 


VII. 


VIII. J 





RESULTS 


OBTAINED WITH 1 RADIATOR OF 


62 SQ. FT. 


1 


13.6 


962 


13083.2 


52 sq. ft. 


251.6 


141.5 


1.77 


5 


14.6 


953 


13913.8 


52 " 


267.5 


153.5 


1.74 


10 


15.8 


945 


14931 


52 " 


287.1 


165.5 


1.73 


15 


16.8 


938 


15758.4 


52 " 


303 


176.5 


1.71 


20 


17.7 


932 


16496.4 


52 " 


317.2 


185.5 


1.70 


3-) 


18.6 


926 


17223.6 


52 " 


331.2 


194.0 


1.70 


30 


19.3 


921 


17775.3 


52 " 


341.8 


200.5 


1.70 



CHAPTEE XXX. 

PIPE COVERING—WHAT IS SAVED THEREBY, AND 
OTHER DATA. 

In a work of this kind I cannot go into the relative 
merits of pipe covering. There are so many things to 
be considered and so many interests involved that it 
would provfe of no special benefit to the steamfitter, 
and would raise endless discussion, with which no one 
would be satisfied. The subject may be treated of 
generally, however, with a great deal of benefit to all 
those concerned, and I will therefore give some gen- 
eral deductions, obtained in 1892 by the author while 
making experiments for the H. W. Johns Mfg. Co. of 
New York. I was assisted by the well-known steam 
engineer, Mr. George H. Barrus, of Boston, whose name 
is a sufficient guarantee of accuracy and integrity in 
trials of this kind. 

The company mentioned were desirous of compar- 
ing not only their own special products relatively, but 
also of comparing them with other well-known cover- 
ings then on the market. 

It is needless to go into the method used, other 
than to say that they were condensation tests, and 

339 



340 8TEAM HEATING FOR BUILDINGS. 

that the utmost precaution was taken to prevent in- 
accuracy. Many experiments and repetitions of the 
experiments were made, until the methods used devel- 
oped a uniformity of results which were in themselves 
a check on all possible mistakes of manipulation or 
observation that were likely to creep in. 

Experiments were always made on a two-inch pipe 
about 16 feet long, and having exactly 10 square feet 
of surface to a pipe. These pipes were called " ele- 
ments" of 10 square feet each, and twelve of them 
were arranged in twelve separate chambers, open top 
and bottom, all within a very large loft of a factory 
where the temperature was nearly constant, and so 
arranged that one could not influence the other. 
Transposition was also resorted to to check inequali- 
ties due to neighboring influences. 

The pressures at which the trials were made were 
50, 100, 150 and 200 pounds, and presumably the 
trials represented the most elaborate experiments 
ever completed in this direction, and it will be a grati- 
fication to the writer could he make the results public, 
but as they are the property of the company who paid 
for them, this cannot be done. Certain deductions, 
however, can be made public, and these I give, with 
the consent of the parties most interested. 

The diagram. Fig. 123, is taken from the report. The 
horizontal lines show pressures of steam in pounds 
above atmosphere. The vertical lines show pounds 
weight of steam condensed per element of 10 square 
feet of pipe surface per hour. The line AB is the line 
of condensation within one of the elements without 
covering. It shows the condensation in an uncovered 
two-inch pipe. The lines marked 1 to 12, inclusive 



J 



PIPE COVERING. 



341 




100 lbs. 150 lbs. 
Diagram, Fig. 



342 STEAM HSJATIHTG FOB BXnLDnrO-B. 

show the amount of condensation for each element for 
twelve selected commercial pipe coverings. The line 
CD is an arbitrary line, conforming to the differences 
of temperature between that of the air and that of the 
steam within the pipe, and shows a remarkable uni- 
formity with lines of condensation. The vertical lines 
at the right show the comparative weights of the differ- 
ent coverings per square foot of pipe surface covered. 

An important deduction to be drawn is that the 
weight of the covering bears a close analogy to the 
efficiency of the covering ; generally the lighter the 
covering, the better it is. It will be noticed that cov- 
ering No. 3 gave the least condensation, and conse- 
quently the highest efficiency ; and it will be seen by 
the vertical lines that its weight was the least. It will 
also be noticed that covering No. 12, the poorest cov- 
ering and the one that gave the highest condensation, 
weighs the most, and is about double the weight of 
No. 3, while the condensation is also approximately 
nearly twice as great. 

Another and startling deduction to be drawn from 
the chart is that the very poorest covering (No. 12) is 
so immensely better than no covering, that where it 
is necessary to save steam or prevent heating or warm- 
ing a room or space, the covering of steam pipes is 
certainly one of the best of investments. I may add, 
*' cover them with anything " rather than leave them 
uncovered. 

The distance from the curved line AB to the base 
line shows the condensation in an uncovered pipe. 
The distance from the other curves to the base line 
gives the condensation according to the covering used. 
It will be noticed that even with the poorest covering, 



PIPE COTERmO. 343 

that from f to f of tlie total condensation due to an 
uncovered pipe can be prevented, while with the best 
of coverings between |- and -|- of the total condensation 
will be prevented. This is the result that went beyond 
tlie author's expectation, and will, no doubt, astonish 
many others, now that it is pointed out ; as, in my 
judgment, few had a full appreciation of the matter. 

In regard to the relative efficiency of the different 
coverings, it will be noticed that the greatest con- 
densation for 10 square feet of surface is 3 pounds 
7 ounces of water in an hour's time (No. 12), when the 
pressure of steam was 200 pounds to the square inch, 
while at 50 pounds pressure of steam it was 2 pounds 
7 J ounces. This was with the poorest covering, while 
at the same time the condensation in the uncovered 
pipe was over 13^ pounds at 200 pounds pressure, and 
nearly 7i pounds at 50 pounds pressure. It will 
further be noticed that the best covering reduced the 
condensation for a pressure of 200 pounds to 2 pounds 
15|- ounces, while at 50 pounds it was but 1 pound 
7 ounces, showing that between a poor and a good cov- 
ering there was a very material difference. In other 
words, the best covering was nearly twice as efficient 
as the poorest. 

The various intermediate results for other conditions 
can be approximated from the diagram. It was ex- 
plained that the line AB was the line of condensation 
in an uncovered pipe. The length of the vertical lines 
intersecting the curved line gives the condensation for 
the different pressures. In like mannei the vertical 
distance from the base line to the ordinates of curves 
gives the condensation for 10 square feet of pipe sur- 
face, covered with the different materials (1 to 12). 



344 



STEAM HEATING FOR BUILDINGS. 



The accompanying table shows the weight of steam 
condensed per hour for each square foot of surface. 
Column No. 1 shows the number of the pipe or ele- 
ment, and refers to the covering used. Columns Nos. 
2, 3, 4 and 5 show the condensation per square foot of 
pipe covered for the various pressures of 50, 100, 150 
and 200 pounds of steam above temperature. Element 
No. 5 indicates the condensation in the uncovered 

pipe. 

TABLE NO. 8. 

POUNDS OP STEAM CONDENSED PER HOUR PER SQUARE FOOT OP 
2 ' PIPE. 



No. of Pipe. 


50 Lbs. 


100 Lbs. 


150 Lbs. 


200 Lbs. 


1 


.1549 


.1854 


.2135 


.2232 


3 


.2091 


.2591 


.2945 


.3178 


3 


.135 


.1602 


.1872 


.197 


4 


.1878 


.2292 


.2574 


.2778 


5* 


.7682 


1.013 




... . 


6 


.1408 


.1681 


.194 


.2007 


7 


.1599 


.1909 


.2194 


.2324 


8 


.1745 


.2069 


.2324 


.2497 


9 


.1703 


.2059 


.2359 


.2532 


10 


.1605 


.1862 


.2182 


.2284 


.11 


.1629 


.1911 


.2209 


.2331 


12 


.2352 


.2885 


.3325 


.3537 


Average of all but 










No. 5 


.1719 


.2065 


.2364 


.2515 



* No. 5 shows the condensation in an uncovered pipe. 

There are other conditions to be considered in 
selecting coverings than efficiency. A covering must 
be permanent, and not easily charred or deteriorated 
by high-pressure steam ; and I mention it here to pre- 
vent a person from selecting a covering by its weight 
alone. 



CHAPTEE XXXI. 

MISCELLANEOUS NOTES. 
CUTTING WALLS AND COVERINa RISERS. 

Architects often omit to leave a recess where re- 
quired in the walls of a building, and the fitter has to 
cut one. In his anxiety to put up as much pipe as 
possible, and as he considers the cutting of the wall 
does not properly belong to him, he cuts it in the 
quickest and easiest manner he can, regardless of the 
appearance, and in some loosely put up walls it is a 
difficult task to make an attractive or even satisfactory 
piece of work. The proper way would be to have the 
openings left and cutting avoided ; but if it must be 
done, it should be well done. 

Let the fitter provide himself with sharp chisels and 
a light hammer, and he can generally cut a brick with- 
out disturbing it in the wall ; but it is also necessary 
for the master mechanic to consider wall-cutting labor, 
and to give the workman to understand he will be 
credited with cutting walls as well as for putting up 
pipe. 

The fitter should get the architect's permission be- 
fore he commences to cut, for otherwise there may be 

345 



346 BTEAM HEATING FOR BUILDINGS. 

mucli i//jury done to a building by liaving a recess cut 
from top to bottom near a front wall or corner, or 
where considerable weight comes on the wall. 

The best way to cover a riser recess is with a board 
lined with %m on its inner side. Have the grounds 
put on bofore the plastering is done, and have the 
panel scrfjwed on afterward. The panel may also be 
fancy iron-work, with holes in it, which makes a very 
peimanent method. A moveable panel admits of access 
to the pipes to make repairs without breaking the 
walls. 

Some architects require the recess to be plastered 
over, using slate or coarse wire-cloth to hold the plas- 
ter, so as to entirely hide the appearance of a pipe, 
but even then they do not entirely succeed, for two or 
three reasons. When a slate is stuck over the recess 
with plaster-of-paris, and plastered over all, the ex- 
pansion of the slate often cracks the plaster. When 
plastered on wire-cloth, it does very well, and will not 
crack, but it will turn a dark color in time, as will any 
thin covering when it becomes warm, because the con- 
tinuous current of air passing up the wall at that par- 
ticular spot deposits more dust there than at any other 
point, and leaves a well-defined mark. 

For the same reason, the walls back of radiators get 
dark more rapidly than the walls of any other part of 
the room. The same is true of curtains which hang 
near a register. In parts of the country where soft 
coal is generally used this is very apparent. 

TURNING EXHAUST STEAM OR VAPOR INTO CHIMNEYS. 

There is a custom among steam-fitters and others 
of turning the exhaust from an engine into the boiler 



. 



MISCELLANEOUS NOTES. 347 

chimney in buildings, ostensibly to " make the draft 
better," but in reality to save running an exhaust pipe 
to the roof of the building. Exhaust steam, turned 
into a long or high brick chimney, will not improve 
the draft, but impair it. 

In locomotives the exhaust steam is turned into the 
stack to increase the draft, and in sliort iron stacks of 
portable engines it has the same effect, when properly 
put in ; but it must be borne in mind, that to be effect- 
ive, it must have such proportions as to make it an in- 
jector, to increase the velocity of the air by contact 
with its own high velocity, before it has time to expand 
and fill the stack. 

In long iron stacks, a little steam turned into them 
may, perhaps, be of some use in warming the stack 
(which cools rapidly from contact with the wind and 
air in cold weather), and by assisting the upward cur- 
rent of smoke or air by mixing with it. Under certain 
conditions, it makes a mixture of steam and air lighter 
than the air alone. If the increased velocity caused 
thereby more than compensates for the extra volume 
which has to pass, it may possibly be an improvement. 

But usually the exhaust steam impairs a long chim- 
ney (especially an iron one), leaving the condensation 
to run down the inside of the chimney in stream Sj and 
to be again partly re-evaporated by absorbing heat 
from the gases of combustion. In brick chimneys this 
is very apparent, condensing and soaking into the 
brick-work, and absorbing as much heat from the 
gases of combustion to re-evaporate and drive off a 
cubic foot of it as would cool 30,000 cubic feet of air 
100 degrees Fahrenheit. It also destroys the chimney. 



348 8TEAM HEATING FOR BUILDINGS, 



SOLDERING OF PIPES AND BRASS FITTINGS. 

Often it is necessary to solder or " sweat '* pipes into 
fittings, or male and female threads of brass work. 
The latter is no trouble, and can be done by tinning 
the parts to be put together, using only resin for a 
flux, if done while new, and then screwing them to- 
gether while hot. When iron pipe has to be sweated 
into iron fittings, malleable iron fittings should be 
used, because they can be tinned by using muriatic 
acid reduced with zinc ; cast-iron does not solder well. 

When about to sweat a pipe and fitting together, 
wipe the threads carefully, and run a carefully-wiped 
die over the male thread, to entirely clean it, using a 
clean tap to remove any oxide or grease from the 
female thread in the fitting ; then tin cleanly, using 
muriatic acid for a flux, and screw the parts together 
while both are hot. 

The assertion is sometimes made that solder will 
melt under high-pressure steam temperatures. This 
I found to be so when the pressure of the steam went 
beyond 180 pounds per square inch. The solder used 
in " sweating " brass pipes together was what is known 
as " half and half " — that is, about one-half tin and 
one-half solder, no bismuth being used that I could 
discover. When the steam pressure was between 180 
and 190 pounds, or at a temperature of about 380° 
Fahr., the solder oozed out of the threads like drops 
of quicksilver, and I found it necessary to make the 
threads tight by screwing alone. Of course this tem- 
perature of 380° or 382° Fahr. is considerably below 
the melting point even of tin (about 444° Fahr.), but it 
was probably sufficient to soften the alloy so that it 



mSGELLANEOUS NOTES. 349 

flowed under the pressure of 180 pounds per square 
inch. 

There is no advantage in soldering a frost burst in 
an iron pipe, through which steam or very hot water 
passes, for it will not last. 

In iron water-pipe, rather than remove the pipe, it 
may be soldered, but it must be thoroughly cleaned 
and tinned, and a heavy wipe joint made on it ; bolt- 
ing is of no avail. 

When cracks appear in brass or copper pipes with- 
out any apparent cause, there is very little use in 
soldering, for they are usually caused by undue ex- 
pansion in adjacent parts of the metal, and are a fault 
of manufacture which soft solder will remedy for a 
very short time only. 

PAINTING PIPES. 

Distributing pipes may be painted with anything that 
will arrest oxidation. Raw linseed oil,witli ochre of the 
required color, and turpentine, form a good prepara- 
tion for radiators, when they are to be bronzed, as it 
gathers and '' fixes " any machine oil or dirt there may 
be on the pipes, and will make a good back for the 
bronze. When radiators are painted steam should be 
turned on immediately, and they should be dried by 
heat. If they are painted with heavy oil paints that 
dry on the surface and are allowed to stand for some 
time, when steam is turned on they will blister. 

White or colored enameled paints make a good 
finish for radiators, but it is difficult to obtain a paint 
that will not change its color under heat. Dead or 
flat paints, with plenty of turpentine, should be used 
first, and the finishing coat should be the enameled 



350 STEAM HEATING FOR BUILDINGS. 

paint. For hot water work enameled jDaints stand 
very well. 

Black baking japan, or black air-drjing japan, are 
Very good substances for painting pipes and iron- 
work, and two coats will give a good gloss, which does 
not require to be renewed. A wipe with a slightly 
oiled woolen cloth will give them a fresh appearance. 
Bronzing cannot be done over a black varnish, which 
will show through many coats of bronze. 

Black paraffiue varnish should not be used, as it is 
not permanent ; it cokes with heat, and has no body. 

Indirect coils, or coils or heaters which cannot be 
seen, it is best not to paint. 

Dust allowed to collect on heaters impairs their 
efficiency very much. 



CHAPTEE XXXII. 

FIRE FROM STEAM PIPES. 

Theke is much diversity of opinion as to whether 
wood, in its simple state, painted or unpainted, or its 
charcoal, will take fire from the heat of steam, un- 
superJieated, at any ordinary pressures. Steam can be 
made so hot by superheating that it will ignite wood, 
and its pressure may be made so high its heat will be 
sufficient to ignite wood; but these are not ordinary con- 
ditions of steam any more than they would be ordinary 
conditions of air, and air also can be warmed either by 
superheating or pressure until it will ignite wood. 
What evidence, therefore, have we that steam at ordi- 
nary conditions will ignite wood or other woody fibres ? 

I have known tampico fibre that was used in the 
manufacture of brushes to fall between the heating 
pipes of the drying room, in which there was almost 
constantly 60 pounds pressure of steam, and although 
it was as fine as bristles, and was packed in between 
pipes, it did not take fire. I have also used pine laths 
on the upper side of the shell of a horizontal boiler, 
to maintain a space, when turning the arch of brick- 
work over the boiler, and in years afterwards, when 
resetting the same boilers, I found these laths in good 

351 



352 STEAM HEATING FOR BmLDINQS. 

condition and not charred, altliougli they were subject 
to the heat of 60 pounds pressure of steam and in 
heavy and close contact with the iron of the boiler, 
with 4 inches of brickwork as a covering to the laths, 
which, of course, prevented any great loss of heat 
through or from the outer surface of the wood. 

The forging and the lagging of engine cylinders with 
wood furnish apparently good evidence against the 
ignition of wood by steam pipes at ordinary low pres- 
sures and at the ordinary condition of steam. 

Superheated steam, however, and very high-pres- 
sure steam can undoubtedly ignite wood. I have seen 
the hair, felt, and canvas burned off the pipes of a heat- 
in/^ apparatus for 20 or 30 feet from the boiler by the 
wator becoming low or the boiler nearly empty and 
the steam becoming superheated. 

In all construction, therefore, care should be taken 
to guard against the contact of the steam pipes with 
wood, as the general danger is undoubtedly increased 
by the omission to do so. 

Some charcoals will ignite at a much lower tempera- 
t ire than others, and it is a well-known fact that the 
'ower the temperature at which charring occurs, the 
ower the temperature of ignition. The question is, 
however, whether the temperature of charring can ever 
become so low as to cause the temperature of ignition 
to become equally low, or nearly as low. 

The question has been discussed in the technical 
schools and societies and by the insurance companies 
without any definite conclusion. I think, however, it 
is well to perpetuate a diagram (Fig. 124) that appeared 
in the Scientific American about twenty j^ears ago, 
which " Mr. Stahl, a student of the graduating class of 



FIRE PROOF STEAM PIPES. 353 

the Stevens Institute of Teclinologj, 23repared, at the 
request of Professor ThurstoD, in which the vertical 
scale is one of temperatures of preparation of charcoal, 
and the horizontal scale is one of tem23eratures of igir 
tion, and the curve shown contains the points of coi 
respondence as given in the table. 

" It will be seen that the curve is apparently nearly 
hyperbolic. The lowest temperature of preparation 
was 500° Fahr., but it is seen at a glance, even that at 
350°, the temperature of steam under a pressure of 
over 125 lbs. per square inch, the temperature of 
preparation and of ignition cannot coincide unless 
some marked change of law should occur at so low a 
temperature, carrying the curve, which here represents 
that law, abruptly inward to reach the point A. It is 
needless to state that such a phenomenon would be 
quite improbable, and is probably impossible." 

The foregoing was the editorial comment that ap- 
peared with the diagram. 

When the writer first saw the above he was induced 
to make some crude experiments in the same d.irection. 

The pine laths that I before mentioned I enclosed 
in a retort, and to prove this, wood was not charcoal, 
I placed it in a retort and drove off gas that burned 
with nearly as much light as illuminating gas when it 
leaves the retort. 

I inclosed a two-inch cube of white pine wood within 
a small gas pipe retort, with a bit of solder (one-third 
tin and two-thirds lead) and a bit of sheet lead, and 
placed the retort in a boiler tube for five days, boiler 
going day and night. At the end of that time the 
wood was pure charcoal, the solder was melted, and 
the lead was not, which goes to show pure charcoal 



354 



STEAM HEATING FOR BUILDINGS. 



can be made at a temperature between 440° and 612° 
Fabr. ; it being understood that the melting point of 
this solder is given at 441° Fahr. and that of the lead 
612° Fahr. 

To prove the above was pure charcoal, i. e., that all 
the hydrocarbon was driven off, I raised the tempera- 
ture of the retort to about 1,200°, but could not drive 
off any more gas. 



0° 

350° 
500° 

1000° 
1500° 
8000° 
S500' 

sooo' 





Fig. 124. 



I then inclosed pine laths against the shell of a 
horizontal boiler, and covered them with a course of 
brick on edge. The pressure of steam in this boiler 
was from 40 to 60 pounds day and night for about 
2} years, except one day a month for cleaning. The 
ends of the laths that came out to the air and flush 
with the brickwork were not near as dark as hemlock 
tanned leather, and the darkest part I could find which 



FIBE PMOOF STEAM PIPES. 355 

was entirely covered with brick was not as dark as 
roasted coffee. This goes to show charcoal cannot be 
made at 300° Fahr., after 2-|- years, under the most 
favorable circumstances, with a furnace fire only 5 feet 
beneath it. 

In experiments on the ignition of charcoal, I found 
that the charcoal made in a boiler tube w^ould not red- 
den at the melting point of lead (612° Fahr.), but would 
at a lower temperature than zinc (770° Fahr.). 

My mode of operation was this way. I passed a 
gas pipe through a fire and blew pure hot air through 
the pipe. I also prepared myself with long, slender 
strips of solder (half and half, and one-third tin and 
two-thirds lead), and wdth strips of lead and zinc, and 
pine shavings, and small pieces of the laths and char- 
coal. 

The pure charcoal would not redden in the same 
blast that just melted the lead, but did in a blast which 
melted it rapidly. When held in a blast which melted 
solder (one-third tin and two-thirds lead, melting tem- 
perature about 500° Fahr.), it showed no signs of fire 
or redness. 

The lath, which was 2J- years in contact with the 
boiler under a course of brick, would become charcoal 
in a temperature which melted half and half solder, 
but would not get a spark on it until I increased the 
temperature to where the needle of lead bent and 
dropped. It was the same with a nicely prepared 
splinter of white pine, and I could see no deviation in 
the action from the splinter of the lath ; they all be_ 
came charred in the blast which melted half and half 
solder, but would not take on a spark until the lead 
melted. 



356 STEAM HEATING FOR BUILDINQ8. 

With a blast that fused a metal 19 parts tin, 31 lead 
and 50 bismuth, melting temperature about 212° Fahr., 
I could not turn tissue paper brown. 

Gunpowder held in the blast which melted the lead 
did not explode until after the lead melted. It gave 
off a slight blue sulphurous light first, then the lead 
melted, and an instant after the powder exploded. 

Illuminating gas will not take fire from a cherry red 
poker, but will from a bright red one. 

The gas of wood, crude petroleum, soft coal, or any 
other hydrocarbon, will not take fire when escaping 
hot from the retort. With a cherry red poker I have 
tried the three mentioned. 



CHAPTER XXXIII. 

STEAM- HEATING DATA. 

The object of tins cliapter is to i3rovide simple and 
approximate preliminaiy data for one wlio desires to 
find the first things necessary for the installation of a 
steam heating or hot-water plant. 

The rules are all based on strictly scientific and 
engineering data, but they are divested of all unneces- 
sary refinement, which for ordinary purposes would 
only add complication to the task, without getting 
very much nearer the actual truth. 

They are the first rules that are required by one 
when designing a building by which he is enabled to 
provide space for boilers, find the horse-power, obtain 
the area of the grate, approximate the coal required, 
find the size of his chimney, etc., and they are the 
rules that the ordinary person wants either to commit 
to memory, or to have at hand in a concise and simple 
form when wanted. 

They are confined to the fewest special factors ; 
some of those factors being obtained by multiplying a 
number of simple factors together. 

When a set of plans is placed on the drawing 
boards, the first consideration is to determine the 
amount of condensation of steam that has to go on 

357 



358 STEAM HE ATI NO FOR BUILDINGS. 

witliiu the buildiDg (when that building is properly 
warmed) by the particular method of heating or of 
heating and ventilation that the owner or the architect 
may desire to adopt. 

The condensation of a building may be found by 
two different methods. One, a very simple one, 
is applied to direct radiation, and one, a little 
more complex, is used when forced ventilation or 
large quantities of air by indirect radiation are 
required. 

The latter method will be considered first, as it 
furnishes an item of data on which to base all our 
other calculations. 

For instance, wdien we find the amount of cooling 
or condensation that is to take place within a building 
in the coldest weather, we then know the amount of 
water that it is necessary to evaporate to do this 
work. Having the amount of water to be evaporated, 
we can then obtain in any order we j)lease, the size of 
the boiler necessary to evaporate the water ; the 
amount of coal or other fuel that will evaporate the 
same water ; the size of the grate on which to burn 
the coal ; the size and height of chimney necessary to 
supply air for combustion ; the size of the radiators 
necessary to condense the steam ; the size of pijDes 
necessary to convey steam or hot water to the radia- 
tors ; and all other attendant data Avhich will develop 
as we proceed. 

Conditions for a School. — Let us take, for instance, 
an ordinary primary school building of eight rooms, 
with say fifty children to a room (an average condition 
for primary schools), and that we have to warm and 
ventilate this building so as to comply with what is 



STEAM-HEATING DATA. 359 

known as the "Massachusetts Law," which provides 
that each occupant of the room has to receive a quota 
of thirty cubic feet of air per minute, which is equiva- 
lent to 1,800 cubic feet of air per hour per chikl. On 
the basis, therefore, of the minimum quantity of air 
allowed by custom or law, and making no allowance for 
the teacher, this will call for the admission of 90,000 
cubic feet of air per hour to the school room. Some 
allowance, how^ever, should be made for the teacher, 
and also some little factor for safety so as to prevent 
working too close to the minimum quantity allowed 
by law or custom, so that it is both reasonable and safe 
for an engineer or a designer to assume that he should 
provide at least for the admission and warming of 
100,000 cubic feet of fresh air in each hour to each of 
the eight principal rooms of an ordinary primary 
school building. 

Quantity of Air Required. — This will call for 800,000 
cubic feet of air per hour for the class rooms alone, 
and at least 200,000 cubic feet of air should be pro- 
vided in addition for ventilation for the other parts of 
the building. Of course, these quantities are subject 
to variation in the judgment and experience of the 
engineer, but for our purpose we will take them as 
above for the sake of an easy and even example in 
our calculation. Therefore, an eight room primary 
school will require about 1,000,000 cubic feet of air 
per hour for its proper ventilation. Usually, enough 
warmth can be admitted with this quantity of air to 
keep the rooms properly and equably warm, although 
it is often customary to use additional direct radiation 
in the halls, etc. 

Temperature of Air at Register. — Having now dis- 



360 8TEAM HEATING FOR BUILDINGS. 

covered the quantity of air necessary for the building, 
we have next to consider what its temperature should 
be as it passes through the registers into the rooms 
of the building. It is usual to maintain a temperature 
of 70° Fahr. within a room. It is a common thing to 
provide in specifications for heating that '*the room 
shall be warmed to 70° Fahr. when the thermometer 
outside is at zero." If the air passes the registers, 
however, at 70°, it will not maintain the temperature 
of the room at 70°, as a certain amount of cooling goes 
on within the room, due to walls and windows. It is 
known, however, that should the air pass the registers 
at a temperature of 100° (giving the Massachusetts 
quantity of air), that it is somewhat more than suffi- 
cient to maintain the temperature of the room at 70° 
even when the temperature outside is at zero. It is 
also known that air passing the registers at 80° or 85° 
(giving the Massachusetts quantity, say 100,000 cubic 
feet j)er hour for the room described) will not main- 
tain the temperature of the room at 70°, when the 
temperature outside drops much below 40°. Accord- 
ing to three (3) different theoretical rales (which it is 
not necessary to mention) assuming average conditions 
of walls and windows with light on two sides of such 
a room as we have selected, we have a loss of 27° ; 
16°, and about 13|^° respectively, but my experience 
has been such that I place it at 30°, and therefore 
base all my calculations for school work on an increase 
of 100° above zero as the lowest safe temperature for 
which I provide means to warm the air. 

^^ Air Units.'' — Having therefore determined that 
the building requires 1,000,000 cubic feet of fresh air 
per hour warmed 100°, we have a result of 1,000,000 



STEAM-HEATING DATA. 361 

X 100° Fahrenheit = 100,000,000, which of course is 
100,000,000 cubic feet of air warmed one degree, and 
which I call 100,000,000 "Air Units;" the air unit 
being the equivalent of warming one cubic foot of air 
one degree Fahr. If now we divide these Air Units by 
an average division of 50, we have reduced the same 
to a value of 2,000,000 Heat Units ; the Heat Unit 
being the equivalent of warming one j)ound of water 
one degree, while the Air Unit is the equivalent of 
warming one cubic foot of air one degree. 

The Air Unit, however, thus adopted, is an arbitrary 
unit, and to be correct should be based on warming a 
cubic measure of air at some constant temperature, 
say at 32° or at zero, or the warming of some constant 
weight of air, irrespective of its temperature. For 
our purpose, however, the divisor 50 is approximately 
correct, and is obtained thus : 

One pound of air at 32° Fahr. under a pressure of 
an atmosphere of 29.9 inches of mercury, Avill occupy 
a space of 12.38 cubic feet, and its specific heat is 
.2379 ; the specific heat of water being unity. In 
other words, a pound of water requires 4.2 times as 
much heat to increase its temperature one degree 
Fahr. as a pound of dry air does ; so that the warming 
of 4.2 pounds of air one degree is the equivalent of 
cooling one pound of water one degree. We have 
thus, 4.2 pounds of air at 32° Fahr., occupying a sj^ace 
of 12.38 cubic feet X 4.2, which equals 52 cubic feet, 
or the bulk of air at a temperature of 32° that can be 
warmed by one Heat Unit. This, as will be noted, is 
for air at 32°. Now, if the air instead of being 32° is 
zero, following the same method of reasoning as we 
have above, its bulk will be 48.6 cubic feet for each 



362 STEAM HEATING FOR BUlLDimS. 

Heat Uuit, and at a temperature of 14° above, its bulk 
is 50 cubic feet ; while at 70° Falir.. it will be 56.2 
cubic feet. This therefore gives the range of bulk for 
air between zero, the coldest outside temperature on 
which calculations are usually made, to 70°, the tem- 
perature of the room, and shows why 50 can be taken 
as a proper divisor without appreciable error. 

British Heat Units. — We have found above, there- 
fore, that for every million cubic feet of air admitted 
to the building in an hour (or any time) and 
warmed 100°, we shall have to furnish steam equal to 
2,000,000 British Heat Units in the same time. To 
warm this quantity of air the equivalent of 2,000,000 
Heat Units, we shall have to cool a quantity of steam 
equal to 2,000,000 Heat Units, and here again another 
average divisor of 1,000 may be used without appre- 
ciable error, by which we obtain the amount of steam 
necessary to be condensed (or to be evaporated), and 
the answer will be in pounds weight of steam or 
water ; which, in the instance we have cited is the 
equivalent of 2,000 pounds weight of steam condensed 
or 2,000 pounds of water evaporated to steam in a 
boiler. 

Heat Units in One Pound of Steam. — Let us now see 
how this divisor of 1,000 is obtained. If we evaporate 
one pound of water from a temperature of 212° (under 
our ordinary pressure of atmosphere) it requires 965 
Heat Units to accomplish the evaporation, and to turn 
the water into steam at a pressure just above the 
atmosphere (according to Regnault's tables), and if 
we look at any of the tables of the heat of steam, we 
shall find that the latent heat of vaporization decreases 
with an increase of pressure, but that the sensible heat 



STEAM-HEATING DATA. 363 

increases, and that the sum of the sensible and latent 
heat of steam above 212° forms a nearly constant 
quantity, increasing slightly with the increase of 
pressure, so that at ten pounds pressure it is the 
equivalent of 974 Heat Units, and at forty pounds 
pressure it is the equivalent of 989 Heat Units, while 
at one hundred pounds pressure it is the equivalent 
of 1,004 Heat Units. I follow this line of reasoning 
on the assumption that we always cool the water in 
the return pipes to 212°, or something below it. 

In low pressure apparatus it cools considerably 
below 212°, so that it is only necessary to cool it to 
178° to extract the whole 1,000 Heat Units from it. 
Therefore the divisor of 1,000 (Heat Units) is ob- 
tained by cooling one pound weight of steam from say 
one pound pressure above atmosphere to water at a 
temperature of about 178° in the return pipes, and 
which would become but 1,004 Heat Units if we cool 
the steam from one hundred pounds jDressure to a 
temperature of 216° in the return pipes, all of which 
are good average conditions. Therefore, the divisor 
of 1,000 is not empirical, but founded on science and 
practice. 

If we therefore divide our 2,000,000 Heat Units by 
our constant of 1,000 (the Heat Units in a pound 
weight of steam), we find that we have to condense 
just 2,000 pounds weight of steam at any ordinary 
pressure, to supply our 2,000,000 Heat Units, neces- 
sary to warm the 1,000,000 cubic feet of air 100° Fahr. 

HoTse-poiver. — Having now discovered that we re- 
quire to evaporate 2,000 pounds of water or condense 
2,000 pounds of steam, we divide this 2,000 by 30, 
and have the result in centennial horse-power ; which 



364 8TB AM HEATING FOR BUILDIiyGS. 

is equivalent to 66.Q horse-power. This, therefore, 
gives us the boiler capacity we have "been looking for. 

Coal. — After having found our boiler it becomes 
necessary to approximate the amount of coal that we 
may have to burn, so that we may be able to estimate 
our expense and also arrive at the size of our grate. 
Having the amount of water that it is necessary to 
evaporate, say 2,000 pounds, a simple method indeed 
is to divide the weight of water in pounds by another 
constant divisor of ten (10) and the result is the 
Aveight of good coal that will be burned to evaporate 
that quantity of water. This ten (10) is also a slightly 
variable quantity, and will vary from eight to eleven 
with different types of boilers. I use the ten for all 
ordinary rough calculations, although some say nine 
may be nearer the actual conditions of common prac- 
tice ; ten being good practice. Therefore, if we divide 
the 2,000 pounds of water by ten, it shows that we 
have to burn about two hundred pounds of coal per 
hour to warm 1,000,000 cubic feet of air 100° in the 
same time. 

Grate. — Having found the amount of coal to be 
burned, it then becomes necessary to establish the 
size grate necessary to burn this coal. It is said that 
in burning coal under large boilers when a fireman 
is in attendance, the greatest results in economy 
have been obtained- when the coal has been burned at 
the rate of about nine pounds per hour per square 
foot of grate. This dictum, however, is open to ques- 
tion. For a low pressure apparatus in house work or 
school work in the care of janitors, and any apparatus 
that is made automatic and that will have to run for 
long periods without attention, four to five pounds of 



STEAM-HEATING DATA. 365 

coal per hour per square foot of grate is ordinary 
practice ; hence the large proportion of grate in small 
boilers. Again, with high pressure power boilers, 
twelve to one, and even higher is not considered bad 
practice. This question, therefore, admits of great 
latitude, but for boilers for all ordinary large buildings 
(power boilers), ten to one and twelve to one becomes 
a good rule. In other words, divide the amount of 
coal by ten or tw^elve, and you have the square feet of 
grate necessary and proper to burn it under average 
conditions of practice. 

The ten to one would give us twenty square feet of 
grate for a sixty-seven horse-power boiler, which is 
rather a larger grate than a sixty-seven horse-power 
horizontal boiler would require, and where ten may 
be a good ordinary divisor, twelve will probably be 
nearer the ordinary and every-day practice, when 
circumscribed by local conditions. 

Chimney. — The next question to consider is that of 
the chimney necessary to burn the amount of coal 
required. The chimnej^, when accurate data are re- 
quired, should be calculated by the amount of coal to 
be burned and the height of the chimney, but this is 
a complex question in itself, and we have no room for 
it here. 

A common old rule for proportioning the size of 
the chimney for the grate, is to take one-eighth of the 
grate area, and call it " chimney." Nothing was said 
about the height of the chimney, and at the best this 
was but a crude approximation, and often disappoint- 
ing with a short chimney, although at the present time 
in New York with high buildings (over one hundred 
fee-t), it is a safe rule to follow. 



366 STEAM HEATING FOR BUILDmQS. 

Recapitulation. — We can now recapitulate tlie whole 
of the foregoing matter in the following simple man- 
ner by an arithmetical example, thus : 

(1) 1,000,000 cubic ft. air passing through build- 
ing in an hour. 
X 100° Fahr. air is warmed (0. to 100. F.) 



50)100,000,000 air-units. 

1,000)2,000,000 Heat-Units required in an hour. 



10)2,000 lbs. water to be evaporated in boiler 
or steam condensed in apparatus 
per hour. 

12)200 lbs. coal required per hour. 
8)16.6 sq. ft. of grate (minimum). 
2.075 sq. ft., size of chimney 100 ft. high. 

The above speaks for itself. 

If now we desire to find only the horse-power of 
the boiler, we divide the number of pounds of water 
to be evaporated per hour by thirty , thus : 

(2) 30)2,000 lbs. 

66.6 horse-power. 

Boiler Surface. — If again we desire to know the 
square feet of surface that such a boiler should have, 
to furnish 66.6 horse-power, you may take "the boiler 
maker's rule " of allowing fifteen square feet per 
horse-power, which is the usual amount provided in 
horizontal multitubular boilers, and we have the 
following simple example : 



STEAM-HBATING DATA. 367 



(3) QQ.Q liorse-power of boiler. 
15 sq. ft. per liorse-power. 



999 sq. ft. of surface in boiler. 

wliicli is practically 1,000 square feet of surface for 
such a boiler. 

The foregoing simple data, therefore, establish 
the amount of air necessary for the school ; the tem- 
perature to which provision should be made for warm- 
ing the air ; the total (British) units of heat necessary 
to warm the air ; the amount of water necessary to be 
made into steam (or steam to be condensed into water) 
necessary to supply the foregoing units of heat ; the 
amount of coal required to be burned per hour ; the 
reasonable size of the grate on which to burn the 
coal; the size of the chimney necessary for com- 
bustion ; the power of the boiler in nominal horse- 
power, and the number of square feet of fire and flue 
surface in the boiler. 

The above is for indirect work for school buildings, 
hospitals, etc., and in the folloAving I will endeavor to 
consider the question of similar calculations when 
based on direct radiation without systematic ven- 
tilation. 

Direct Radiation, — Having determined the amount 
of direct radiating surface necessary for warming a 
room or for a building, it becomes necessary to know 
how to obtain the boiler, etc., for the same. The 
radiating surface for the building may be determined 
by any of the ordinary rules of practice, a very good 
one of which appeared in the early editions of this 
work, but which was omitted accidentally in the gen- 
eral revision of the 14:th edition. It is to be found at 



368 STEAM HEATING FOR BUILDINGS. 

the end of tliis chapter in connection with the matter 
omitted, and has been known as the "Author's Rule." 
It has stood a test of over twenty years and can be 
relied upon. 

Having found or established the radiating surface, 
therefore, we can proceed as follows : 

Multiply the heating surface in square feet, either 
by the number of pounds of steam that it is known the 
particular type of radiator will condense in an hour, 
or by the number of heat units when that is known, 
and which is pretty well established for different 
types of radiators and coils. 

Horizontal coils of plain pipe, well distributed, have 
the highest efficiency as direct heaters. Then come 
the simple types of vertical radiators, when not of 
too great a height. The higher a radiator is, the 
lower its efficiency per square foot of surface, and 
thirty-six or thirty-eight inches has been established 
as a fair limit of height, so as to prevent an unnec- 
essary waste of floor room, with reasonable economy 
in iron and in cost. 

Condensation. — Without going into the matter in 
detail, therefore, it is only necessary for me to say 
that in horizontal one inch pipe in wall coils, the 
condensation per square foot of surface is found to 
be about .3 of a pound of water per square foot 
per hour for low pressures (one or two pounds pres- 
sure of steam), and that it decreases to about .25 of a 
pound of water per square foot per hour for the aver- 
age types of radiators. 

Taking the value, therefore, of a pound of steam at 
1,000 Heat Units, we have 300 Heat Units per square 
foot of surface for coils, which in some cases run a 



STEAM-HEATING DATA. 369 

little over this, and 250 Heat Units per square foot 
of surface for average radiators. Tlie condensation, 
however, will vary and increase with an increase of 
pressure of steam, and numerous experiments have 
demonstrated that the condensation in different types 
of radiators and coils can be reduced to the equiva- 
lent of 1.66 Heat Units per degree difference, between 
the temperature of the air of the room and the 
temperature of the steam, per square foot of heating 
surface, for the poorer types, to about 2.25 Heat 
Units for the more efficient direct radiators and coils. 

Assuming, therefore, that w^e have a radiator of 100 
square feet in a room at 70°, with a pressure of steam 
at one pound, or 215°, we have a difference of temper- 
ature between the steam and the air of the room of 
145°, and should the type of radiators or coils be un- 
known to us, other than that the building is to be 
Avarmed by direct radiation, it is reasonable to assume 
that we may average the loss of heat per square foot 
of surface per degree difference of temperature at 
two Heat Units, which is my usual practice unless I 
know^ exactly what type the radiators are to be, and 
which gives us a total loss of heat of 290 Heat Units 
per square foot of surface for a radiator of 100 square 
feet, therefore the loss of heat is equivalent to 29,000 
Heat Units, or say the condensation of twenty-nine 
pounds of steam, while for a building of 1,000 square 
feet of surface, it will amount to 290,000 Heat Units, 
and so on. 

For the sake of easy calculation, therefore, we will 
assume that we have a building with 10,000 square 
feet of radiation, and desire to find the boiler, etc., we 
may proceed as follows : 



370 STEAM HEATING FOR BUILDINGS. 

(4) 10,000 sq. ft. of radiation in building. 

290 Heat Units lost per sq. ft. per liour, 

1,000)2,900,000 Total Heat Units. 

10)2,900 lbs. Water to be evaporated or 
steam to be condensed per hour. 
12)290 lbs. coal required per hour. 

8)24.16 sq. ft. of grate. 

3.2 Area of chimney in sq. ft. 100 feet 
high. 

The horse-power of the boiler and the surface in 
square feet can be found as shown before in examples 
(2) and (3). 



Empirical Eules. 

Simple empirical rules based on the foregoing are : 

(1) Heat Units. — Having the cubic feet of air to 
pass through a building in an hour and warmed 100° 
Fahr,, multiply it by two (2), and the answer is in 
Heat Units. 

(2) Pounds Weight of Steam. — Having the cubic feet 
of air to pass through a building in an hour, and 
warmed 100° Fahr., desiring the weight of steam 
required to warm same, divide by 500, and the answer 
is in po2inds iveight of steam. 

(3) Coal Required. — Having the cubic feet of air to 
pass through a building in an hour, and warmed 100° 
Fahr., and requiring the amount of coal to be burned 
per hour, divide by 5,000, and the answer is in pounds 
iveight of coal.. 

(4) Size of Grate. — Having the cubic feet of air to 



STEAM-HEATING DATA. 371 

pass through a building in an hour, and warmed 100° 
Fahr., and requiring the grate area, divide by 60,000, 
and the answer is in square feet of grate. 

(5) Size of Chimney. — Having the cubic feet of air 
to pass through a building in an hour, and warmed 
100° Fahr., and requiring the chimney 100 feet high, 
divide by 500,000, and the answer is in square feet of 
cross sectional area. 

(6) Required Horse-power. — Having the cubic feet 
of air to pass through a building in an hour, and 
warmed lOO'' Fahr., and requiring the horse-power of 
the boiler, divide by 15,000, and the answer is in horse- 
power. 

(7) Boiler Surface. — Having the cubic feet of air to 
pass through a building in an hour, and warmed 
100° Fahr., and require the number of square feet of 
heating surface in boiler, divide by 1,000, and the 
answer is in square feet. 

The Author's Eule. 

To Estimate the Amount of Heating Surf ace Necessary 
to Maintain the Heat of the Air of Enclosed Space in 
Buildings to the Desired Temperature. — The old method 
of taking the contents of a room or building and 
dividing it by some fixed factor to find the heating 
surface is now entirely obsolete, as it should be, as it 
was not based on anything but the most arbitrary 
principles. 

It may be resorted to now in a rough way when 
making preliminary estimates of cost, the price per 
cubic foot being known approximately by comparison 
with other buildings whose cost is known. 



372 STEAM HEATING FOB BUILDINGS. 

When it is considered, however, that a room of 
1,000 cubic feet may be a cube of 10 X 10 X 10 with 
one cold side in one case, while with three cold sides 
in another, it is quite evident that it will require 
nearly three times as much heating surface in one 
case as in the other, so that this alone shows the 
error of estimating heating surface by cubic contents. 

The heating surface necessary to warm a room, of 
course, should be proportional to the cooling surface, 
and the glass of the Avindows and the outside walls 
form the largest factors in cooling. 

The glass which forms the windows forms the 
highest cooling factor in ordinary practice, and it may 
be taken as 1,000, in which case the following table 
shows approximately the value of other building 
materials. 



TABLE OF APPKOXIMATE POWEE FOR TEANSMITTING HEAT 

OF VAEIOUS BUILDING SUBSTANCES COMPAEED WITH 

EACH OTHEE. 

Window glass 1,000 

Oak and walnut sheathing on walls 66 to 100 

White pine and pitch pine 80 to 100 

Lath and plaster, walls good 75 to 100 

common 100 to 150 

Common brick (rough) 150 

'•' (hard finish). , 200 

" (hollow walls, hard finish) 150 

Sheet iron 1,100 to 1,200 

A square foot of glass and a square yard of ordinary 
outside wall have about the same cooling value. 



STEAM-HEATING DATA, 373 

It has been found that one square foot of heating 
surface with steam at one pound pressure will just 
about offset the cooling done by two square feet of 
glass, when the outside temperature is 70°. This is so 
well established now that it need not be questioned. 

In the early days of steam heating the Avriter was 
acquainted with this fact, and he devised the follow- 
ing rule, which appeared in the first edition of this 
work in about 1879. 

Divide the difference in temperature^ hetioeen that at 
ivhich the room is to he kept and the coldest outside atmos- 
phere, by the difference betiveen the temperature of the 
steam pipes and that at ivhich you wish to keep the room, 
and the product ivill he the square feet, or fraction thereof 
of plate or pipe surface to each square foot of glass (or its 
equivalent in wall surface). 

Thus : Temperature of room, 70 degrees ; less tem- 
perature outside, ; difference, 70 degrees. Again : 
Temperature of steam pipe, 212 degrees ; less tem- 
perature of room, 70 degrees ; difference, 142 degrees. 
Thus : 70 -^ 142 — . 0.493, or about one-half a square 
foot of heating surface to each square foot of glass, or 
its equivalent. 

It must be distinctly understood that the extent of 
heating s.urface found in this way offsets only the 
windows and other cooling surfaces it is figured 
against ; and does not provide for cold air admitted 
around loose windows, or between the boarding of 
poorly constructed wooden houses or for ventilation. 
These latter conditions, when they exist, must be 
provided for separately, and usually require as much 
as 50 per cent, additional ; a good common rule for 
ordinary purposes being three-fourths of a square 



374 STEAM HEATING FOR BUILDINOS. 

foot of heating surface to eacli square foot of glass, 
or its equivalent in wall surface. 

In isolated buildings, exposed to prevailing north 
or west winds, there should be a generous addition 
of the heating surface on the exposed sides of the 
rooms. 

In green-houses the saving of heat when double 
glazed sashes are used is very apparent, and in build- 
ings warmed altogether by direct radiation \ io ^ less 
heating surface will do when double windows are used. 



CHAPTER XXXIV. 

MISCELLANEOUS NOTES AND TABLES. 

These notes and tables will be found of service in 
estimating. 

The avoirdupois pound is always to be used, unless 
otherwise specified. It contains 7,000 Troy grains ; the 
grain is always Troy. 

16 drams = 1 ounce. oz. 

16 ounces = 1 pound. lb. 

25 pounds = 1 quarter. qr. 

4 quarters = 1 hundred. cwt. 

20 cwt., 2,000 lbs. = 1 ton. 

The gross ton (in which the quarter becomes 28 lbs., 
the hundredweight, 112 lbs., and the ton, 2,240 lbs.) is 
used in estimating English goods at the U. S. Custom- 
House ; in freighting ; in the wholesale coal trade ; and 
in the wholesale iron and plaster trades, and when 
specified. 

1 lb. avoir, = 16 oz. avoir. = 7,000 grs. Troy. 
1 " « = 437.5 " 

27-^ cubic inches of water weigh one pound avoir- 
dupois, at a temperature of 40°. 

375 



376 STEAM HEATING FOB BUILDINGS. 

A cubic foot of water, at a temperature of 60°, weighs 
999 ozs., and is taken as 1,000 ounces, or 62|^ pounds, 
for all ordinary calculations. It weighs a little less 
than 60 pounds when the temperature is 212°. 

A cubic foot of water contains very nearly 7^ gallons, 
and for rough calculations may be taken as such 
(7.4805 gallons is actual) number. 

A cubic inch of water, at its greatest density, weighs 
252.725 grains ; a cubic foot, 62.4 pounds. 

1 gal. = 231.0 cubic in. 



1 cub. ft. 


, 71 " = 1728.0 


1 bushel, 1 ^ 


<< 


9^" =r 2150.42 


1 cord, 128.0 


« 


" = 


1 cub. yd., 27.0 


« 


" = 46656.0 


1 barrel,^ 4.21 


« 


314 " = 7276.5 



* A flour barrel will hold 33.28 gallons, or 4.449 cubic feet, or 2.79 
heaped bushels (called 2^ bushels). 

In estimating quantities of water by barrels, 31^ standard gallons 
equals the barrel. 

TABLE No. 9. 

WEIGHT OF A CUBIC INCH OF VARIOUS METAI.S. 



Iron, cast . 263 of a pound. 

" wrought 0.28 " 

Lead 0.41 « 

Copper 0.32 «^ 

Nickel 0.30 * 

Steel 0.28 *•' 

Tin 0.265 « 

Zinc, cast 0.24 " 

" rolled 0.26 «« 

Brass, steam metal 0. 315 " 

" yellow 0.282 *♦ 



MI8GELLANE0US NOTES AND TABLES. Zll 

TABLE NO. 10. 

mteight of a cubic foot of various building materials, in pounds 
(approximate). 

Granite 168.0 pounds 

Marble 165.0 " 

Sandstone ... 135.0 " 

Blue-stone 165.0 " 

Slate 180.0 « 

Mortar, dry 80.0 to 100 pounds. 

Common Brick 112 . pounds. 

Dry Sand 100.0 " 

Fire-brick 135.0 " 

One perch of stone-work, in walls or foundations, 
measures 24f cubic feet. 

One thousand common bricks, laid in a wall, makes 
about 50 cubic feet, varying a little for different bricks. 

Six fire-bricks to each square foot of lining, one 
brick thick, is sufficient ; 1,000 bricks will make 170 
superficial feet of lining, laid in the ordinary way. 

To find the weight of iron castings by computation. — 
Find its solid contents, in inches, and multiply them 
by 0.26, and it will give the weight, in pounds. For 
rough calculations, it will do to divide the cubic inches 
by 4, and call the answer pounds. 

To find the weight of any other casting, or forging. — 
Find its solid contents in cubic inches, and multiply by 
the weight of a cubic inch of the metal, as given in the 
table No. 9, "Weight of a cubic inch of various metals." 

For irregular castings, which are difficult to measure 
and cannot be conveniently weighed, a rough estimate 
of their weight may be taken, provided they are not 
cored out, by weighing the pattern, if it is of soft pine, 
and allowing 13 times the weight of the pattern, if it 



378 



STEAM HEATING FOR BUILDINGS, 



is new, or just out of the sand, and 14 times if it has 
laid in the pattern loft for some time. 

A square foot of cast-iron, one inch thick, weighs 
37|^ pounds. To find what a square foot of any other 
thickness will weigh, multiply 37|- by the thickness in 
inches, or fractions of an inch. 

A square foot of rolled wrought-iron, one inch thick, 
weighs 40 lbs. To find the weight of boiler plates, or 
sheet-iron, per square foot, multiply 40 by the decimal 
of an inch in thickness the required plates are to be. 

TABLE No. 11. 

THE FOLLOWING TABLE SHOWS THE DIFFERENCE BETWEEN AMERICAN ANI 

ENGLISH WIRE GAUGES, AND THE THICKNESS OF PLATES, IN 

DECIMALS OF AN INCH FOR EACH. 



No. of Gauge. 


American. Inches. 


English. Inches. 


0000 


0-46 


0.454 


000 


0.4096 


0.425 


00 


0.3648 


0.38 





0.3248 


0.34 


1 


0.2893 


0.3 


2 


0.2576 


0.284 


8 


0.2294 


0.259 


4 


0.2043 


0.238 


5 


0.1819 


0.22 


6 


0.1620 


0.203 


7 


0.1442 


0.18 


8 


0.1284 


0.165 


9 


0.1144 


0.148 


10 


0.1018 


0.134 


11 


0.0907 


0.13 


12 


0.0808 


0.109 


13 


0.0719 


0.095 


14 


0.0640 


0.083 


15 


0.057 


0.072 


16 


0.05 


0.065 


17 


0.045 


0.058 


18 


0.04 


0.049 


19 


0.035 


0.042 


20 


0.031 


0.035 



MI8GELLANE0U3 N0TE8 AND TABLM8. 379 

To find tlie weight of a cast-iron pipe, for one foot of 
its length.— Multiply the diameter of the pipe in 
inches by 3.1416, and multiply the answer thus ob" 
tained by the thickness of the pipe in inches, or deci- 
mals of an inch, then by 12 and 0.26 respectively ; or, 
instead of the last two, use 3.15. 

This will give about the weight of the pipe, includ- 
ing the hubs, as the outside circumference of the pipe 
is not the mean length of the iron, according to its 
thickness. To be exact. Proceed as above, but take 
one thickness of the iron from the diameter of the pipe 
first, and it will give the weight of the pipe without 
hubs or flanges. 

Example. — Required the weight of a 12-inch pipe, f 
inch thick, for one foot of its length. Thus : 12. in. — 0.5 
=11.5 X 3.1416 = 36.127 X 0.5 =18.063 X 3.15=56.89 
pounds. 

The 3.15 is the product of 12 inches for the length 
and 0.263 for the weight. 

Definitions and computation's in mensuration^ required 
by the steam-Jitter. 

The perimeter of a figure is its outer boundary, with, 
out regard to shape. 

A true circle forms the shortest perimeter for the 
greatest area inclosed, and is called a circumference. 

A diameter is a right line, passing through the center 
of a circle. 

A diameter is very nearly -f^ of the circumference 
of the same circle, or, to be exact, 0.3183 of it. Eule. — 
Multiply the circumference by 0.3183, and it will give 
the answer, in the same denomination. 

A circumference is 3^/^ ^^ ^^^ diameter of the same 
circle very nearly, or, to be exact, 3.1416. 



380 STMAM HEATING :^0n BmLDINGB. 

The square of the diameter of a circle is multiplying 
it once hj itself. Thus, if the diameter is 4, the square 
will be 16. (4 inches X 4 inches = 16 inches.) 

To find the area (the number of square inches) 
within a circle.— Multiply the square of the diameter 
by 0.7854, and it will give the answer in the same de- 
nomination as it was squared in. Thus, 4'' X ^" = 16'' 
X 0.7854 = 12.566 square inches, whose diameter is 4 
inches. 

The cube of a number is the number multiplied by 
itself twice. Thus, 4 X 4 =: 16 X 4 = 64. 

When the cube of the diameter of a sphere is mul- 
tiplied by 0.5236, it gives the solid contents, in num 
bers of the same denomination as it was cubed in. 
Thus : 4'' X 4'' = 16^' X 4^' = 64'' X 0.5236 = 33.51 
cubic inches, for a ball four inches in diameter ; and 
when multiplied again by 0.263 it gives 8.813, which 
will be the weight in pounds of a cast-iron ball of the 
same diameter. 

A cylinder of the same length as its diameter has 
the same surface as a sphere of equal diameter (sur. 
face of ends, of course, not included). 

To find the surface of a cylinder 4 inches in diameter 
and 4 inches long.— Multiply the diameter by 3.1416 
and the product by the 4 inches in length. Thus, 
4 X 3.1416 = 12.566 X 4 = 50.2656, the square inches 
on the outside of a 4 X 4 cylinder. 

To find the surface of a sphere 4 inches in diameter. 
— Square the diameter, and multiply by 3.1416. Thus : 
4 X 4 = 16 X 3.1416 = 50.2656. 

To find the outside surface of a pipe. — Multiply the 
outside diameter in inches by 3.1416, and by the length 
in inches, and divide by 144 ; it will give the answer 
in square feet. 



MISCELLANEOUS NOTES AND TABLES. 



381 



To find the pressure, per square inch, a column of 
water of any height will exert. — Multiply the height 
of the column, in feet, by the weight of a cubic foot of 
water in pounds at the temperature the water may be, 
and divide by 144. 

Example. — Eequired the pressure, per square inch, 
of a head of water of 200 feet, and when the tempera- 
ture of the water is 40° Fahr. (weight 62^ pounds). 
Thus, 200 X 62.5 = 12500 ~ 144=86.8 pounds per 
square inch. 

Required the pressure of the water at a temperature 
of 212°. Thus, 200 X 59.80 = 11960^144 =83.05 
pounds per square inch. 

TABLE No. 12. 

THE FOLLOWING TABLE OF DIAMETERS, CIRCUMFERENCES, AND AREAS 
IS GIVEN FOR "READY-RECKONING." 



Diameter. 


Circumfer- 
ence, 


Area. 


Diameter. 


Circumfer- 
ence 


Area. 


lV 


0.1963 


0.0030 


r^ 


4.5160 


1.6229 


i 


0.3927 


0.0122 


i 


4.7124 


1.7671 


-h 


0.5890 


0.0276 


-h 


4.9087 


1.9175 




0.7854 


0.0490 


f 


5.1051 


2.0739 


f 


0.9817 


0.0767 


4 


5.3015 


2.2365 


1.1781 


0.1104 


? 


5.4978 


2.4052 


■fff 


1.3744 


0.1503 


if 


5.6941 


2.5801 


i 


1.5708 


0.1963 


i 


5.8905 


2.7611 


^^ 


1.7671 


0.2485 


If 


6.0868 


g.9483 


1 


1.9635 


0.3068 








u 


2.1598 


0.3712 


2 in. 


6.2832 


3.1416 




2.3562 


0.4417 


h 


6.4795 


3 3411 


4 


2.5525 


0.5185 


i 


6.6759 


3.5465 


1 


2.7489 


0.6013 


1. 

1 6 


6.8722 


3.7582 


if 


2.9452 


0.6903 


i 


7.0686 


3.9760 








A 


7.2649 


4.2001 


lin. 


3.1416 


0.7854 




7.4613 


4.4302 


-h 


3.3379 


0.8861 


'I'e 


7.6576 


4.6664 


i 


3.5343 


0.9940 


\ 


7.8540 


4.9087 


'1^^ 


3.7306 


1.1075 


-i%- 


8.0503 


5.1573 


i 


3.9270 


1.2271 


i 


8.2467 


5.4119 


h 


4.1233 


1.3529 


H 


8.4430 


5.6737 


t- 


4.3X97 


1.4348 


i 


8.6394 


5.9395 



382 



MISCELLANEOUS NOTES AND TABLES. 



Diameter. 


Circumfer- 
ence. 


Area. 


Diameter. 


Circumfer- 
ence. 


Area. 


n 


8.8357 


6.2126 


i 


17.2788 


23.7583 


i 


9.0321 


6.4918 


A 


17.4751 


24.3014 


if 


9.2284 


6.7772 


i 


17.6715 


24.8505 








H 


17.8678 


25.4058 


3 in. 


9.4248 


7.0686 


4 


18.0642 


25.9672 


-iV 


9.6211 


7.3662 


^1 


18.2605 


26.5348 


i 


9.8175 


7.6699 


i 


18.4569 


27.1085 


'h 


10.0138 


7.9798 


A 


18.6532 


27.6884 


i 


10.2102 


8.2957 








■h 


10.4065 


8.6179 


6 in. 


18.8496 


28.2744 


t 


10.6029 


8.9462 


-h 


19.0459 


28.8665 


■i-6 


10.7992 


9.2806 


i 


19.2423 


29.4647 


\ 


10.9956 


9.6211 


-5_ 

1 1) 


19.4386 


30.0798 


■N 


11.1919 


9.9678 


i 


19.6350 


30.6796 


f 


11.3883 


10.3206 


i% 


19.8313 


31.2964 


n 


11.5846 


10.6796 


1 


20.0277 


31.9192 


1 


11.7810 


11.0446 


l\ 


20.2240 


32.5481 


if 


11.9773 


11.4159 


1 


20.4204 


33.1831 


¥ 


12.1737 


11.7932 


'1% 


20.6167 


33.8244 


n 


12.3700 


12.1768 


f 


20.8131 


34.4717 








i^ 


21.0094 


35.1253 


4 in. 


12.5664 


12.5664 


f 


21.2058 


35.7847 


tV 


12.7627 


12.9622 


ii 


21.4021 


36.4505 


^ 


12.9591 


13.3640 


i 


21.5985 


37.1224 


1^ 


13.1554 


13.7721 


n 


21.7948 


37.8005 


X 


13.3518 


14.1862 








1% 


13.5481 


14.6066 


7 in. 


21.9912 


38.4846 


1 


13.7445 


15.0331 


■h- 


22.1875 


39.1749 


-j2jj 


13.9408 


15.4657 


i 


22.3839 


39.8713 


i 


14.1372 


15.9043 


>% 


22.5802 


40.5469 


A 


14.3335 


16.3492 


JL 
4 


22.7766 


41.2825 


? 


14.5299 


16.8001 


-.% 


22.9729 


41.9974 


1^ 


14.7262 


17.2573 


f 


23.1693 


. 42.7184 


f 


14.9226 


17.7205 


•fff 


23.3656 


43 4455 


11 


15.1189 


18.1900 


i 


23.5620 


44.1787 


i 


15.3153 


18.6655 


-A 


23.7583 


44.9181 


n 


15.5716 


19.1472 


f 


23.9547 


45.6636 








i^ 


24.1510 


46.4153 


5 in. 


15.7080 


19.6350 


f 


24.3474 


47.1730 


tV 


15.9043 


20.1290 


if 


24.5437 


47.9370 




16.1007 


20.6290 


i 


24.7401 


48.7070 


t 


16.2970 


21.1252 


if 


24.9354 


49.4833 


16.4934 


21.6475 








'1% 


16.6897 


22.1661 


8 in. 


25.1328 


50.2656 


^ 


16.8861 


22.6907 


1^6- 


25.3291 


51.0541 


17.0824 


28.2215 


i 


S5.5255 


51.8486 



STEAM HEATING FOR BUILDINGS. 



383 



Diameter. 


Circumfer- 
ence. 


Area. 


Diameter. 


Circumfer- 
ence. 


Area. 


-1% 


25.7218 


52.8994 


f 


86.9138 


108.4342 


i 


25.9182 


53.4562 


i 


37.3065 


110.7536 


A 


26.1145 


54.2748 








f 


26.3109 


55.0885 


12 in. 


37.6992 


113.0976 


'h 


26.5072 


55.9138 


i 


88.0919 


115.4660 


i 


26.7036 


56.7451 


I 


88.4846 


117.8590 


1% 


26.8999 


57.5887 


1 


38.8773 


120.2766 


i 


27.0963 


58.4264 


i 


39.2700 


122.7187 


i^ 


27.2926 


59.7762 


1 


88.6627 


125.1854 


f 


27.4890 


60.1321 


f 


40.0554 


127.6765 


if 


27.6853 


60.9943 


i 


40.4481 


130.1923 


i 


27.8817 


61.8625 








it 


28.0780 


62.7369 


13 in. 


40.8408 


132.7326 








i 


41 2338 


135.2974 


9 in. 


28.2744 


63.6174 


I 

4 


41.6262 


137.8867 


iV 


28.4707 


64.5041 


1 


42.0180 


140.5007 


i 


28.6671 


65.3968 


i 


42.4116 


143.1391 


A 


28.8634 


66.2957 


i 


42.8044 


145.8021 


i 


29.0598 


67.2007 


1 


43.1970 


148.4896 


A- 


29.2561 


68.1120 


i 


43.5857 


151.2017 


f 


29.4525 


69.0293 








16 


29.6488 


69.9528 


14 in. 


43.9824 


153.9884 


i 


29.8452 


70.8883 


i 


44.3751 


156.6995 


1% 


30.0415 


71.8121 


1 

4 


44.7676 


159.4852 


i 


30.2379 


72.7599 


1 


45.1605 


162.2956 


H 


80.4342 


73.7079 


i 


45.5532 


165.1303 


I 


30.6306 


74.6620 




45.9459 


167.9896 


H 


80.8269 


75.6223 


1 


46.3386 


170.8735 


i 


31.0233 


76.5887 


i 


46.7313 


173.7820 


H 


81.2196 


77.5613 














15 in. 


47.1240 


176.7150 


10 in. 


31.4160 


78.5400 


i 


47.5167 


179.6725 


i 


31.8087 


80.5157 


i 


47.9094 


182.6545 


i 


32.2014 


82.5160 


1 


48.3021 


185.6613 


1 


32.5941 


84.5409 


i 


48.6948 


188.6923 


i 


32.9868 


86.5903 


f 


49.0875 


191.7480 




33.3795 


88.6643 


1 


49.4802 


194.8282 


f 


83.7722 


90.7627 


I 


49.8729 


197.9330 


i 


84.1649 


92.8858 














16 in. 


50.2656 


201.0624 


11 in. 


84.5576 


95.0334 


i 


50.6583 


204.2162 


i 


34.9503 


97.2053 


1 

4 


51.0510 


207.3946 


1 

4 


85.3430 


99.4121 


1 


51.4447 


210.5976 


t 


35.7357 


101.6234 


i 


51.8364 


213.8251 


i 


36.1284 


103.8691 


i 


52.2291 


217.0772 


f 


36.5211 


106.1894 


f 


52.6218 


220.3537 



384 



STEAM HEATING FOR BUILDINGS. 



Diameter. 


Circumfer- 
ence. 


Area. 


Diameter. 


Circumfer- 
ence. 


Area. 


i 


53.0145 


223.6549 


f 


67.1517 


358.8419 








i 


67.5444 


363.0511 


17 in. 


53.4073 


226.9806 




67.9371 


367.2849 


i 


53.7999 


230.3308 


3. 


68.3298 


371.5432 


i 


54.1926 


233.7055 


i 


68.7225 


375.8261 


f 


54.5853 


237.1049 








i 


54.9780 


240.5287 


22 in. 


69.1152 


380.1336 




55.3707 


243.9771 


i 


69.5079 


384.4655 


55.7634 


247.4500 


1 


69.9006 


388.8220 


^ 


56.1561 


250.9475 


f 


70.2933 


393.2031 








i 


70.6860 


397.6087 


18 in. 


56.5488 


254.4696 




71.0787 


402.0388 


1 


56.9415 


258.0161 


a. 


71.4714 


406.4935 


57.8342 


261.5872 


i 


71.8641 


410.9728 


1 


57.7269 


265.1829 










58.1196 


268.8031 


23 in. 


72.2568 


415.4766 




58.5123 


272.4479 


i 


72.6495 


420.0049 


■ 


58.9056 


276.1171 


1 

4 


73.0422 


424.5577 


i 


59.2977 


279.8110 


f 


72.4349 


429.1352 








i 


73.8276 


433.7371 


19 in. 


59.6904 


283.5294 




74.2203 


438.3636 




60.0831 


287.2723 


i 


74.6130 


443.0146 


60.4758 


291.0397 


i 


75.0057 


447.6992 


f 


60.8685 


294.8312 








i 


61.2612 


298.6483 


24 in. 


75.3984 


452.3904 




61.6539 


302.4894 


i 


75.7911 


457.1150 


^ 


62.0466 


306.3550 


! 


76.1838 


461.8642 


•^ 


62.4393 


310.2452 


1 


76.5765 


466.6380 








i 


76.9692 


471 4363 


20 in. 


62.8320 


314.1600 




77.3619 


476.2592 


i 


63.2247 


318.0992 


1 


77.7546 


481.1065 


1 

4 


63.6174 


322.0630 


i 


78.1473 


485.9785 


i 


64.0101 


326.0514 










64.4028 


330.0643 


25 in. 


78.5400 


490.8750 


|. 


64.7955 


334.1018 


i 


78.9327 


495.7960 


a 


65.1882 


338.1637 


4 


79.3254 


500.7415 


■^ 


65.5809 


342.2503 


1 


79.7181 


505.7117 








i 


80.1108 


510.7063 


21 in. 


65.7936 


346.3614 




80.5035 


515.7255 


i 


66.3663 


350.4970 


1 


80.8962 


520.7692 


i 


66.7590 


354.6571 


i 


81.2889 


525.8375 



To find the circumferences of larger circles, multiply the diamete 
by 3.1416. For areas, multiply the square of the diameter by 0.7854. 



MISCELLANEOUS NOTES AND TABLES, 



385 



TABLE NO. 13. 

SHOWINQ THE NUMBER OF FEET IN LENGTH OF VARIOUS SIZED PIPES 
WHICH WILL CONTAIN ONE CUBIC FOOT OF WATER. 



Nominal Size 
of Pipe. 


Length in feet which 

will contain one cubic 

foot. 


Nominal Size 
of Pipe. 


Length in feet which 

will contain one cubic 

foot. 


i 


470.0 


^ 


14.6 


\ 


270.0 


4 


11.3 


1 


167.0 


4i 


9. 


u 


96.5 


5 


7.2 


u 


70.5 


6 


5. 


2 


43.9 


7 


3.54 


2^ 


30.0 


8 


2.875 


3 


19.35 


9 


2.26 



By multiplying the above lengths by the relative 
volume * of steam at any required pressure, it will 
give the length of pipe which will be necessary to con- 
tain a cubic foot of water when converted into steam 
at that pressure. This is necessary in ascertaining 
the amount of water that will be taken from a boiler 
to fill the pipes and radiators of the apparatus with 
steam. 

To make the subject of horizontal multi-tubular 
boilers complete for the class of men who do not find 
it convenient or cannot spare the time to figure the 
matter out for themselves, or who may not have the 
data at their fingers' ends, the annexed table (No. 14) 
and diagram have been worked out to cover the prin- 
cipal points connected with this class of boilers. 

The diagram Fig. 125 of the head-sheets shows the 
number of tubes of the ordinary sizes in general use 
that can be properly and conveniently ^put into the 
head-sheets of boilers from 36 inches to 60 inches in 
diameter, at the same time leaving sufficient room 

* See Table No. 5, page 195. 



386 STEAM HEATING FOR BUILDINGS. 

above the tube line to form a steam space and allow 
sufficient distance for a safe water line. 

The diameters of boilers and tubes given cover tho 
common range of sizes used in warming. An empiric 
cal rule exists among some boiler constructors to have 
one-fourth of the diameter of the boiler above the tube 
line to allow for steam space and water above the 
tubes. This may do on boilers of large diameter, but 
for 36 and 42 inch boilers, practice has proved that it 
is not sufficient — at least in boilers that are to be used 
for warming purposes with gravity apparatus. When 
a boiler has to supply steam for engines and power 
steadily, and has a continuous and regular feed supply 
that will keep the water within a range of rise and fall 
of two inches, then the minimum water and steam 
space of J can be used as a good common rule, pro. 
vided tube surface enough cannot be properly placed 
in less than the remaining three-fourths of the boiler, 
heads. But this one-fourth rule should not be followed 
in boilers under 48 inches in diameter, even for power 
and seldom in boilers for heating purposes, or for 
heating purposes and power combined. 

The reason for this is well known to the experienced 
steam-heating engineer, and is obvious when it is ex 
plained that a boiler or a battery of boilers must have 
sufficient water above the tube lines to allow for the 
filliijg of all the mains and heater with steam without 
lowering the water to a dangerous point. 

A novice about a steam-heating boiler will have an 
experience about as follows : He will get up steam 
and fill his mains and radiators to, say five pounds 
pressure. As the water lowers in his boiler he adds 
fresh water to maintain the water line, say "two 




DIAGRAM OF BOILER-HEADS 
Fig. 125. 



\To face page 386,.] 



% 



MISCELLANEOUS NOTES AND TABLES. 387 

cocks." As soon as the water of condensation begins 
to come back lie finds the water will rise in his boiler, 
and it puzzles him a little. However, he shortly 
realizes it is the return water, and goes to the blow-off 
cock and lets some of it out. Soon he gets his heat- 
ing apparatus in " train," and the water " stands " all 
right, and his first scare is over. Then he receives an 
order to " run the pressure up " to 50 pounds. Away 
goes the water again ; in fact, it has been lowering in 
the glass since the pressure began to increase. Cau- 
tion drives him to the pump, and he puts the water up 
to " two cocks " again, and all goes well for a time. 
Then he receives an order to open the doors and let 
the pressure down, and from that moment he is in 
trouble again, and it may be he will find he has water 
enough coming from some place to fill the boiler to 
the safety-valve, and he goes again to the blow-off 
cock. 

Now, all this is wrong. There should be sufficient 
water above the tubes of such boilers to fill the mains 
and radiators with steam at the highest pressure likely 
to be carried, without having to add more, unless some 
has been wasted by blowing into the sewer or else- 
where. 

If the filling of the mains and radiators of a steam 
apparatus with steam at five pounds pressure takes IJ 
inches of water from a boiler, it will take 4|- inches if 
the pressure is run up to 50 pounds, and to this should 
be added 2|- inches for safety, making the level of the 
water at the starting of the fire seven inches or more 
above the tube line. 

Exactly what this distance should be cannot be 
accurately established, and will be different in different 



388 81 E AM HEATma FOB BUILDINGS, 

apparatus, increasing with the bulk of steam within 
the radiators, as compared to the surface of the radi- 
ators. 

For the above reason another empirical rule was 
given for a general determination of the water line 
and the steam space above the water, and good prac- 
tice had established this to be about two-fifths of the 
diameter of the boiler. 

On the other hand, again, we are generally con- 
fronted with the necessity of getting the largest pos- 
sible tube surface in a given size shell, on account of 
the restricted width and height of the space allowed 
for boilers in most of our large buildings. As a com- 
promise between the two empirical rules the boiler 
heads shown in the diagram have been laid out in 
every case to give about one-third of the diameter of 
the boiler above the tube line, and to be as near the 
two-fifths line as is consistent with getting a reasonable 
tube area, both in regard to heating surface and flue 
area. 

The rule has been to keep all tubes three inches 
from the shell of the boiler, as called for in the laws 
governing marine boilers, and. in these diagrams no 
tube comes nearer the shell than 2|- inches. 

There are two instances, also, in which a greater 
distance can be obtained between the tube line and 
the top of the boiler-shell than shoAvn in the diagrams, 
and that is in the case of the 36-inch boiler, with 
thirty-nine 2J^-incli tubes, and the 48-inch boiler, with 
thirty-nine 3|^-inch tubes. In both cases the tubes 
could be dropped l-J inches without bringing them too 
close to the shells. 

It appears unnecessary to explain the object of Table 



MISCELLANEOUS NOTES AND TABLES. 389 

No. 14 ; it shows for itself. It was made bj the author 
for his own convenience, and its use must be apparent 
to any one who wishes to know how many tubes he 
can put into a certain diameter boiler without resort- 
ing to the drawing board to lay it out for himself. 
Thus he finds the number in column 4, and the size of 
the tubes in column 2. Then he finds the heating 
surface of the boijer for given lengths in square feet 
in columns 8 and 9, but it does not include the upper 
half of the shell, which should not be counted. If, 
then, he wants the surface for other lengths of boiler 
he finds the number of square feet of surface he is to 
add or take away for each foot the boiler is longer or 
shorter than for the columns 8 and 9. The columns 
10 and 11 give the tube area, the first in square inches 
and the latter in square feet. Columns 18 and 19 give 
the horse-power, assuming 15 square feet of average 
shell and tube surface to be one nominal horse-power 
in this class of boilers. 

In the diagram, where tubes are dotted they can be 
dropped to good advantage, as being either too near 
the shell or in the way of inspection. 

The thickness and areas of tubes used are those 
given by the National Tube-Works. 



390 



STEAM HEATING FOR BUILDINGS. 



CO 


5 

3 




fl 


•S 


•So 


Ib 


u 


%i 


"fl 




H 

•s 


is 


^1 


1 


1 <D^ 


II 


Ii 


1^ 

^45 


Hi 


«s 


a3^ 


i« 


Htf 


or 


is? 


^%% 


fis' 


S52 


•■sSl 


-J 

a 

1 


S a 
a 


&l8 


II 
ll 










"SI 


III 


s 


h 


"i 


^ 


1 


= 3 


%i 


c3 © 


^1 


Q 


H 


« 


s 


^ 


.M 


^^ 


^^ 


^^ 


^ 


36 


2 


?^ 


M 


62 


2.110 


34.09 


416.16 




159.526 


36 


2 


1 


1 


52 


2.110 


29.35 


359.26 




133.796 


36 


2J^ 


1 


1 


39 


1.674 


28.00 


343.06 




159 516 


36 


3 


1 




32 


1.370 


28.06 


343.78 




194.240 


36 


3 




1 


26 


1.370 


23.68 


291.22 




157.820 


36 


4 


m 


1 


16 


1.024 


20.33 


251.06 





175.024 


42 


214 


1 


1 


58 


1.674 


40.14 


491.31 




237.220 


42 


3 


1 


1 


45 


1.370 


38.34 


469.68 




273.150 


42 


3 




1 


39 


1.370 


33.96 


417.17 


... 


236.730 


42 


3^ 


la 


1 


30 


1.172 


31.03 


382.62 




250.410 


42 


4 


1 


26 


1.024 


30.88 


380.22 




284.414 


48 


2J^ 


1 


1 


72 


1.674 


49.29 


604.06- 


801.20 


294.48 


48 


3 


1 


1 


57 


1.370 


47.88 


587.19 


778.64 


345.99 


48 


3 


1^ 


1 


52 


1.370 


44.24 


543.32 


720.24 


315.64 


48 


'i}4 


1 


39 


1.172 


39.55 


487.16 


645.36 


3<>5.533 


48 


4 


1^ 


1 


32 


1.024 


37.53 


4'62.92 


613.04 


350.048 


54 


2^ 


1 


1 


100 


1.674 


66.80 




1084.67 


409.00 


54 


3 


1 


1 


72 


1.370 


59.62 





969.79 


437.04 


54 


3 


ii 


1 


69 


1.370 


57.43 




934.75 


418.88 


54 


3Vli 


1 


54 


1.172 


53.14 




866.11 


450.738 


54 


4 


1 


45 


1.024 


51.01 


....... 


832.03 


492.255 


60 


m 


1 


1 


127 


1.674 


83.71 




1359.05 


519.43 


60 


3 


1 


1 


100 


1.370 


80.84 




1313.13 


607.00/ 


60 






1 


92 


1.370 


75.00 




1219.69 


558.44 


60 


31^ 


VA 


1 


69 


1.172 


66.72 




1087.21 


575.94 


60 


4 


Wx 


1 


56 


1.024 


62.53 




1020.17 


612.58 


1 


2 


3 


4 


5 


6 


7 


8 


9 


10 



TABLE NO. 14. 



MISCELLANEOUS NOTES AND TABLES. 



391 





i 

Is 

n-S 


s 


SI 






■-i 




II 


1 


r 


u 
II 


=1 


if 
55 


•S.O 


1 
1 


"So 


1.107 


2.573 

3.573 
4.090 
6.079 
6.079 
10.939 


13 
14 
13 
13 

15 


13 
13 
12 
12 
12 
10 


.095 
.095 
.109 
.109 
.109 
.134 


1.900 
1.900 
1.500 
1.273 
1.273 
.955 


.560 
.560 
.819 
.990 
.990 
1.627 


27.75 
23.95 
22.86 
22.91 
19.41 
16.74 




0.929 




1.107 




1.348 




1.095 




1.815 









1.647 


4.090 
6.079 
6.079 
8.347 
10.939 


16 


12 
12 
12 
11 
10 


.109 
.109 
.109 
.120 
.134 


1.500 
1.273 
1.273 
1.090 
.955 


.819 

.990 

.990 

1.274 

1.6^7 


32.75 
31.31 
27.81 
25.57 
2.J.34 




1.896 




1.643 




1 737 




1.974 








2.045 


4.090 


19 


12 


.109 


1.500 


'.819 


40.27 


53.41 


2.402 


6.079 


19 


12 


.109 


1.273 


.990 


39.14 


51 90 


2.191 


6.079 


19 


12 


.109 


1.273 


.990 


36.22 


48.01 


2.260 


8.347 


18 


11 


.120 


1.090 


1.274 


32.57 


43 02 


2.430 


10.939 


19 


10 


.134 


.955 


1.627 


30.86 


40.86 


2.840 


4.090 
6.079 
6.079 
8.347 
10.939 


20 
20 
20 
20 
20 


12 
12 
12 
11 
10 


.109 
.109 
.109 
.120 
.134 


1.500 
1.273 
1.273 
1.090 
.955 


.819 

.990 

.990 

1.274 

1.627 




72 31 


3 0;J5 




64 65 


2.908 




62.31 


3.130 




57 74 


3.418 





55.46 


3.607 


4.090 


21 


12 


.109 


1.500 


o819 




90.60 


4.215 


6.079 


21 


12 


.109 


1.273 


.990 




87.54 


3.878 


6.079 


21 


12 


,109 


1.273 


.990 




81.31 


4.000 


8.347 


21 


11 


.120 


1.090 


1.274 




72.48 


(Table 


10.939 


21 


10 


.134 


.955 


1.627 




68.01 


14) 


















11 


12 


13 


14 


15 


16 


17 


18 


19 



TABLE NO. 14..— {Continued.) 



VLATE 1. 







PLATE II. 



HORIZONTAL STEEL BOILER 

LENGTH 16' DIAMETER 54" 
Boiler Makers Details. 





m 



TOP OF SFAM 








HP 



PLATE II. 



HORIZONTAL STEEL BOILER 

LENGTH 16' DIAMETER 54" 
Boiler Makers Details. 




NTi 



HORIZONTAL MULTITUBULAR BOILER 




HALF FRONT ELEVATION 
AND HALF SECTION 




LONGITUDINAL SECTION 




ooooooooo 
GOOOOOO 



^-1 , ! 




SECTION AT BACK 



PLATE IV. 




PLAN 




CENTER LONGITUDINAL SECTION 



BATTERY. 42-IN. HEATING 
BOILERS. 

AUTOMATIC DRAUGHT DOORS 
ON SIDE. 




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FRONT EUEVATION AND PART SECTION 



CENTER LONGITUDINAL SECTION 



JTAL BOILER. 

FULL FRONT. 



PLATE V. 




4- 



Hi 




<?■* 



LAN OF WALLS FLOOR LEVEL 




60-lN. HORSZONTAL BOILER. 

STEAM-FITTER'S DETAIL. FULL FRONT. 



m 









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1 


















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1 








1 

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"v 






-U'-l"- 




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WALL 



ill 




Sectional View of Fitzgibbons Vertical Marine Boiler. 
PLATE VII. 




-~ _ ^--^zIS^^ 



The Bigelow-Manning Boiler. 
PLATE IX. 




PLATE XI. 
The Root Water-tube Boiler. 



i^feSe^^ 





fG Water-tube Boiler. 
LATE XIII. 




The Stirling Water-tube Boiler. 
PLATE XIII. 



INDEX. 



CHAPTER I. 

GRAVITY-CIRCULATING APPARATUS. 

PAGE 

Gravity Systems of Piping 1 

Nomenclature 6 

Water-line 8 

How a Building with Wooden Floors is Piped 11 

Two Heaters from the Same Connection 12 

Outlets of the Risers 12 

Risers 13 

Radiator Connections 14 

Steam-mains (see Chapter XV) 15 

Return of the Water under all Conditions of Pressure 16 

The Size of Mains 16 

How Steam-pipes should leave the Boiler 18 

Relief Pipes 18 

Pitch of the Main 18 

Tees in a Main 19 

Stop-valves in Risers 21 

Stop-valves in Mains 21 

Main Return-pipes 22 

Dry Return-pipes 23 

Check- valves in Returns 24 

Circulating Pipe 25 

CHAPTER II. 

RADIATORS AND HEATING SURFACES. 

Vertical Tube Radiators 27 

Cast-iron Sectional Radiators 28 

Steam entering Radiator 29 

393 



394 INDEX. 

PAOB 

Description of Plate I 30 

Plane Surfaces (Definition) 32 

Extended Surfaces (Definition) 32 

Bundy Radiator 33 

Reed Cast-iron Loop Radiator 34 

Box Coil 34 

Gold Pin Radiator (Indirect) 35 

Gold's Compound Coil Surface 36 

Coils 39 



CHAPTER III. 

CLASSES OF RADIATION. 

How Direct-radiating Surfaces should be placed 43 

Coils and Radiators in Schoolrooms 44 

Indirect Radiators 44 

Indirect-radiator Boxes 45 

Air-flues 46 

Change of Air in Rooms 47 

Direct-indirect Radiation 48 

The Action of Air in Rooms with Indirect Heaters 61 

Coil Casings, etc 52 

Switch- valve and Arrangement of Indirect Surface for Schools . 64 



CHAPTER IV. 

HEATING SURFACES OF BOILERS. 

Fire-box and Flues 56 

Crowding the Fire-box with Hanging Surfaces 58 

Corrugated Fire Surfaces 59 

BoUers, Fire Tube, Length of 60 

Proportioning Boilers 60 

Can a Boiler be Robbed of its Heat by the Gases of Combustion? 60 

Reverberatory or Drop-flue Boilers 61 

Will the Quantity of Water within a Boiler effect Evaporation? 62 

Old Types Marine Boilers , . . ? 67 



INDEX. 395 

CHAPTER V. 

BOILERS FOR HOUSE HEATING. 

PAOB 

Requirements for House Boilers 63 

Construction of Upright Boilers 65 

Construction of Horizontal Boilers 66 

Contracted Passages under Boilers 66 

Technical Names of Parts of Boilers, and their Setting 67 

CHAPTER VI. 

FORMS OF BOILERS USED IN HEATING. 

A Source of Danger to the Fitter 70 

Upright Boiler without Tubes 71 

Upright Multi-tubular Boiler 72 

Upright with Steam-dome 73 

Upright Drop-tube Boiler 74 

Base-burning Boiler 78 

Mills Cast-iron Sectional 80 

Mercer Cast-iron Sectional 80 

Gurney Cast-iron Sectional 81 

Cottage 83 

Doric 84 

Bundy 85 

Other Cast-iron Boilers 86 

Horizontal Multi-tubular Boilers 90 

Fire-tube Boilers 94 

Water-tube Boilers 95 

CHAPTER VII. 

GENERAL REMARKS ON BOILER SETTING. 

Thickness of Walls 99 

Marshy or Sandy Ground 99 

Why Boiler Walls crack 99 

Fire-bricks in a Furnace 100 

Front-connection Division 102 

Dead Plates 103 

Bridge-walls 103 



396 INDEX, 

PAOB 

Ash-pits 103 

Lugs on Boilers 104 

Suspended Boilers from I Beams 105 



CHAPTER VIII. 

PROPORTION OF THE HEATING SURFACES OF BOILERS TO THE 
HEATING SURFACES OF BUILDINGS. 

Relation of Boiler to Heating Surface of a Building 107 



CHAPTER IX. 

GRATES AND CHIMNEYS. 

Grate of a House Boiler 113 

Size of Grate to Boiler 114 

Evaporation per Pound of Coal 114 

Air-space in Grates 115 

Size of Chimneys 117 

Testing Efficiency of Chimney by Water Gauge 122 

Theoretical Intensity of Chimney 123 

Table of Grates 125 

Why Grates Break 126 

CHAPTER X. 

SAFETY-VALVES. 

Boilers bursting when working at Ordinary Pressures 129 

The Office of the Safety-valve 130 

Decrease of Pressure under the Valve 130 

Table of Lift of a 4-inch Valve at Various Pressures 131 

Graphic Illustration of the Size of the Opening of a 4-inch Valve 

when blowing off at Various Pressures 131 

Formulse for Calculating the Size of Safety-valves 132 

Construction and Operation of Safety-valves 135 

Ordinary Safety-valve with Auxiliary Attachment 136 

Water-column Safety-valve : 137 

Safety-valve with Pipe carried below Water-line 139 

Pop Safety-valves 139 

To calculate Weight necessary to retain given Pressure ; 141 



INDEX. 397 

CHAPTER XI. 

DRAFT REGULATORS. 

PAGE 

Diaphragms 143 

Construction of Regulators 144 

High-pressure Draft Regulators 145 

Connecting Regulators 146 

How Regulators are attached to Ash-pit Doors 147 

Setting Doors for Regulators 147 

CHAPTER XII. 

AUTOMATIC WATER-FEEDERS. 

Construction 148 

When a Water-feeder should be used 151 

Connections to Water-feeders 152 

Draft in Pipes 152 

Fluctuations of Water in a Gauge Glass 153 

CHAPTER XIII. 

AIR-VALVES ON RADIATORS. 

Where they should be Placed 154 

Drawing Air from Coils, etc 155 

Old-style Air-valves 158 

Modern Air-valves 159 

Vacuum Air-valves, etc „ 161 

CHAPTER XIV. 

STEAM PIPE, SIZE, AREA, EXPANSION, ETC. 

Description of Pipe 164 

Nominal Size of Pipe 164 

Table of Standard Dimensions of Pipes 165 

How to Calculate the Relative Areas of Pipes 167 

Table of Relative Areas of Pipes 169 

Diagram of Relative Areas of Pipes 171 

Expansion of Pipe and its Relation to Steam-mains 172 



398 INDEX, 

PAOB 

Expansion of Return-pipes .„ .„ .. 173 

Effect of Lime and Moisture on Pipes 173 

Expansion of Pipes buried in the Ground 174 

Expansion-joints and how to Compensate without them 175 

Connecting Boiler, Domes, etc 176 

Expansion of Cast and Wrought Iron 178 

A Table of Linear Expansion of Wrought- and Cast-iron Pipes 179 



CHAPTER XV. 

SIZE OF MAIN-PIPES FOR LOW-PRESSURE STEAM-HEATING. 

Size of Mains 181 

Loss of Heat from Imperfect Apparatus 182 

Heat or Power necessary to put Water into Boilers 183 

Poor Economy to use Small Piping 184 

Necessity for providing for a Direct Return 185 

How to determine the Size of the Main 187 

The Unit of Size in Pipes 187 

Relation between Heating Surface and Diameter of Pipe 188 

Diagrams of the Size of Main-pipes for Gravity Apparatus .... 188 

Rules for Pipe Diameters 189 

CHAPTER XVI. 

STEAM. 

Temperature of Steam 192 

Technical Terms 193 

Table of Elastic Force, Temperature, and Volume of Steam. . . 195 

Calculations on Steam, Water, etc 197 

Diagram of Rankine's Formula 198 

CHAPTER XVII. 

HEAT OF STEAM. 

The Unit of Heat 200 

Sensible and Latent Heat of Steam 200 

A Diagram of Sensible and Latent Heat of Steam and Water . 202 

Equivalents of Heat 204 



INDEX. 399 

CHAPTER XVIII. 

AIR. 

PASB 

What Air is 206 

Air necessary for an Adult 207 

Expansion of Air 209 

Watery Vapor in the Atmosphere 211 

Quantity of Moisture Air is capable of taking up 211 

Drying Power of Air 213 

A Table of the Watery Vapor Air capable of taking up 213 

What does Ventilation cost? 215 

CHAPTER XIX. 

HIGH-PRESSURE STEAM USED EXPANSIVELY IN PIPES FOR POWER 
AND HEATING. 

Systems 218 

New York Steam Co.'s System 220 

CHAPTER XX. 

EXHAUST STEAM AND ITS VALUE. 

Thermal Value 233 

How Hot can Feed-w^ater be made 234 

What Percentage of the Coal Heap does the Heating of the 

Feed-water represent 236 

How Much of the Exhaust Steam can be used in warming the 

Feed-water 236 

Warming Buildings with Exhaust Steam 236 

Loss from Back Pressure 236 

Exhaust and Live Steam in the Same Coils 240 

CHAPTER XXI. 

EXHAUST-STEAM HEATING. 

Piping 241 

Two Kinds of Steam used in Heating Sytems 242 

General Plan of an Office-building Plant 243 

Exhaust Steam used in Feed-water 244 



400 INDEX. 

PAGE 

Grease Separator 245 

Check- valve 245 

Reducing-pressure Valve 247 

Receiving Tank and Pump Governor 249 

Pumps 249 

Place for Grease Separator 250 

CHAPTER XXII. 

THE SEPARATION OF GREASE FROM EXHAUST STEAM. 

Effect of Grease in Boilers 251 

Size an Important Feature 252 

Method of Separation 252 

Kind and Size of Tanks used 253 

Advantage of Large Tanks to act as Mufflers on Heating System 254 

Operation of the Baldwin Grease Separator 255 

Combined Grease Separator and Feed-water Heater 258 

CHAPTER XXIII. 

BOILING AND COOKING BY STEAM, AND HINTS AS TO HOW THE 
APPARATUS SHOULD BE CONNECTED. 

Steaming in the Atmosphere 260 

Connections to Steamers 260 

Kind of Pipe to be used 261 

Vapor Pipe 261 

Water Seal 262 

Steaming under Pressure 263 

Steam-kettles 266 

Reason why Large Connections to Kettles should be used .... 268 

Warming Water in Tanks 270 

Warming Water for Bath and Laundry Purposes 271 

Steam Roasting Ovens 276 

CHAPTER XXIV. 

DRYING BY DIRECT STEAM. 

Description 277 

Laundry-drying 278 

Dry Kilns and Other Modes of Drying 283 



INDEX. 401 

CHAPTER XXV. 

DRYING BY AIR CURRENTS. 

PAOB 

Drying Bricks 287 

Expense of moving Air with Fan 288 

Moving Air by Means of an Aspirating Chimney (Fig. 113) .... 290 
Why Goods appear Damp when removed from the Drying 

Room 291 

CHAPTER XXVI. 

STEAM TRAPS. 

Object of Steam Trap 292 

Two Classes of Traps, Atmospheric and ^Closed 292 

Direct-return Trap — Its Principle and Operation 293 

Automatic Steam Trap 296 

Open Float or Pot Trap 299 

Modifications of the Pot Trap 299 

Kieley "Return Trap" 304 

CHAPTER XXVII. 

VAIiVES FOR RADIATORS. 

Kind of Valve to use 305 

Radiator connected with Globe Valve showing Reason why 

they should not be used 306 

Johnson Pneumatic System 310 

CHAPTER XXVIII. 

REMARKS ON BOILER CONNECTIONS AND ATTACHMENTS. 

Feed Pipes 312 

Check-valves 312 

Blow-off Cocks 313 

Safety-valves 314 

Gauge or Try Cocks 315 

Glass Water Gauges 315 

Steam Gauges 316 

Main Steam-pipe for Heating Apparatus 316 



402 INLEX. 

CHAPTER XXIX. 

DATA ON CONDENSATION IN RADIATORS. 

PASS 

Results of Tredgold's Experiments 318 

Results of Tredgoid and Hood's Experiments 320 

To Calculate Heat Units radiated per Square Foot per Hour 

per Degree Difference of Temperature 324 

Effect of Glass Windows in a Room 324 

Effect of Wind on Glass 325 

Results of Barrus' Experiments 327 

Results of the Writer's Experiments 327 

Denton and Jacobus' Experiments with Extended Surfaces . . . 329 
Results of Tests made on some of the Regular Makes of Sec- 
tional Cast-iron Radiators by the Writer 330 



CHAPTER XXX. 

PIPE COVERING WHAT IS SAVED THEREBY, AND OTHER DATA. 

Analogy of Weight to the Efficiency 342 

Relative Efficiency of the Different Makes 343 

Results of Tests on Twelve Different Makes of Covering (Table 

No. 8) 344 

Other Conditions than Weight to be considered in selecting a 

Covering 344 

CHAPTER XXXI. 

MISCELLANEOUS NOTES. 

Cutting Recesses or Chases for Risers 345 

Covering Recesses 346 

Turning Exhaust Steam or Vapor into Chimneys 346 

Soldering of Brass Feltings 348 

Action of Solder under High Pressure 348 

Frost-bursts 349 

Painting Pipes 349 



INDEX, 403 

CHAPTER XXXII. 

FIRE FROM STEAM-PIPES. 

PAGE 

from Superheated Steam 351 

Results of Stahl's Experiments on Preparation of Charcoal . . . 352 
Results of Writer's Experiments 353 



CHAPTER XXXIII. 

STEAM-HEATING DATA. 

Conditions for School Heating and Ventilation 358 

Quantity of Air required 359 

Temperature of Air at the Register 359 

Explanation of Air Unit 360 

British Thermal Units required to heat Air 361 

British Thermal Units per Pound of Steam 362 

Weight of Steam required 363 

Coal Consumption necessary 364 

Grate Area to burn Coal required 364 

Chimney Proportions ..>... 365 

Recapitulation of Data 366 

Boiler-surface required 366 

Direct Radiation 367 

Condensation of Steam in Radiators and Coils „ 368 

British Thermal Units per Square Foot of Surface 369 

Example of Calculation of Direct Radiation 370 

Empirical Rules 370 

Heat Units required for a given Air-supply. 

Weight of Steam 

Coal 

Grate 

Chimney 

Horse Power 

Boiler-surface 

The Author's Rule for Direct Radiation =. 371 



404 INDEX. 

CHAPTER XXXIV. 

MISCELLANEOUS NOTES AND TABLES. 

PAGE 

Weight of a Cubic Inch of Various Metals (Table No. 9) 375 

Weight of a Cubic Foot of Various Building Materials in Pounds 

(Table No. 10) 376 

To find the Weight of Iron Castings by Computation 376 

To find the Weight of Irregular Castings 376 

Weight of Various Building Materials 377 

Difference between American and English Wire Gauges and the 

Thickness of Plates, in Decimals of an Inch (Table No. 11). 378 
Definitions and Computations in Mensuration required by the 

Steam Fitter, etc., etc 379 

Diameters, Circumferences, and Areas (Table No. 12) 381 

Number of Feet in Lerigth of Various-sized Pipe which will 

contain One Cubic Foot of Water (Table No. 13) 385 

Horizontal Multi-tubular Boilers 386 

Boiler Data (Table No. 14) 390 



ADVERTISEMENTS 



The Author offers his services as a Consuhing 
Engineer in Power-House Work, Boiler Plants, 
Underground Systems, and the Ventilation and 
Warming of Buildings. 



WILLIAM J. BALDWIN 

Member American Society of Mechanical Engineers 

Member American Society of Civil Engineers 

Associate American Institute of Architects 



AUTHOR OF 

HOT WATER HEATING AND FITTING 

AN OUTLINE OF VENTILATION AND WARMING 

DATA FOR HEATING AND VENTILATION 

BALDWIN ON HEATING 

THE VENTILATION OF THE SCHOOL ROOM 



Address : WORLD BUILDING 

NEW YORK CITY 




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2 



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Gurney Sectional Safety Water Tube Boiler 

Also made in Push Nipple Type 





MONASH No. 5. 
Self Cleaning Air 
Valve for Drip and 
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MONASH No. 9. 

Automatic Hot Water 

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MONASH 
IMPROVED No. 6. 

Four-way-drain 
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MONASH CLASS C-1. — Diaphragm Reducing Valve for Vacuum Systems. 

WE MAKE PISTON REDUCING VALVES ALSO, TO MEET 
VARIOUS CONDITIONS AND REQUIREMENTS 






HIGH GRADE OUR SPECIALTY 

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